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Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 30 to 34 FAMILY AND MONEY     The modern world is changing family relationships. The cost of living has had an influence on how the American family behaves. It may not be the best thing.      Several decades ago, the father went to work. His paycheck paid the bills. The mother stayed home.  She might have volunteered at a local church or a community program. Children went to school.  Sometimes they had a small job on weekends when they were teenagers.      In many parts of the United States, things are different. The cost of living is on the rise. The greatest increases in the cost of living are seen in property prices and in health care. Basically, one salary is not enough to buy or rent a house and pay the bills. As a result, both parents must work. This helps the family keep a roof over their heads, and they can go to the doctor when they need to.      When both parents work, it changes the amount of time that the child spends with them. Many parents put their children in day care. This has the benefit of ensuring the children’s care. But it also reduces the amount of time that parents spend with their children in their early years. What is more, day care is an extra expense. Both parents must work more.      During the school years, it is often the case that children come home before their parents do. They are called latchkey kids because they let themselves in the door. Mother is not waiting at home to open the door for the child. This time alone puts him at risk to things like drugs or crime. The child may get in trouble more often because he is not supervised.           Rising expenses are changing how families live. While working hard for better lives, they open themselves up to different risksThe word “that” in the passage refers to ______ 
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 30 to 34 FAMILY AND MONEY     The modern world is changing family relationships. The cost of living has had an influence on how the American family behaves. It may not be the best thing.      Several decades ago, the father went to work. His paycheck paid the bills. The mother stayed home.  She might have volunteered at a local church or a community program. Children went to school.  Sometimes they had a small job on weekends when they were teenagers.      In many parts of the United States, things are different. The cost of living is on the rise. The greatest increases in the cost of living are seen in property prices and in health care. Basically, one salary is not enough to buy or rent a house and pay the bills. As a result, both parents must work. This helps the family keep a roof over their heads, and they can go to the doctor when they need to.      When both parents work, it changes the amount of time that the child spends with them. Many parents put their children in day care. This has the benefit of ensuring the children’s care. But it also reduces the amount of time that parents spend with their children in their early years. What is more, day care is an extra expense. Both parents must work more.      During the school years, it is often the case that children come home before their parents do. They are called latchkey kids because they let themselves in the door. Mother is not waiting at home to open the door for the child. This time alone puts him at risk to things like drugs or crime. The child may get in trouble more often because he is not supervised.           Rising expenses are changing how families live. While working hard for better lives, they open themselves up to different risksThe author mentions latchkey kids in order to 
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 30 to 34 FAMILY AND MONEY     The modern world is changing family relationships. The cost of living has had an influence on how the American family behaves. It may not be the best thing.      Several decades ago, the father went to work. His paycheck paid the bills. The mother stayed home.  She might have volunteered at a local church or a community program. Children went to school.  Sometimes they had a small job on weekends when they were teenagers.      In many parts of the United States, things are different. The cost of living is on the rise. The greatest increases in the cost of living are seen in property prices and in health care. Basically, one salary is not enough to buy or rent a house and pay the bills. As a result, both parents must work. This helps the family keep a roof over their heads, and they can go to the doctor when they need to.      When both parents work, it changes the amount of time that the child spends with them. Many parents put their children in day care. This has the benefit of ensuring the children’s care. But it also reduces the amount of time that parents spend with their children in their early years. What is more, day care is an extra expense. Both parents must work more.      During the school years, it is often the case that children come home before their parents do. They are called latchkey kids because they let themselves in the door. Mother is not waiting at home to open the door for the child. This time alone puts him at risk to things like drugs or crime. The child may get in trouble more often because he is not supervised.           Rising expenses are changing how families live. While working hard for better lives, they open themselves up to different risksThe word “ensuring” in the passage is closest in meaning to 
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 30 to 34 FAMILY AND MONEY     The modern world is changing family relationships. The cost of living has had an influence on how the American family behaves. It may not be the best thing.      Several decades ago, the father went to work. His paycheck paid the bills. The mother stayed home.  She might have volunteered at a local church or a community program. Children went to school.  Sometimes they had a small job on weekends when they were teenagers.      In many parts of the United States, things are different. The cost of living is on the rise. The greatest increases in the cost of living are seen in property prices and in health care. Basically, one salary is not enough to buy or rent a house and pay the bills. As a result, both parents must work. This helps the family keep a roof over their heads, and they can go to the doctor when they need to.      When both parents work, it changes the amount of time that the child spends with them. Many parents put their children in day care. This has the benefit of ensuring the children’s care. But it also reduces the amount of time that parents spend with their children in their early years. What is more, day care is an extra expense. Both parents must work more.      During the school years, it is often the case that children come home before their parents do. They are called latchkey kids because they let themselves in the door. Mother is not waiting at home to open the door for the child. This time alone puts him at risk to things like drugs or crime. The child may get in trouble more often because he is not supervised.           Rising expenses are changing how families live. While working hard for better lives, they open themselves up to different risksAccording to the passage, which of the following is true of the cost of living 30 years ago?
Read the following passage and mark the letter A, B, C, or D on your answer sheet to choose the word or phrase that best fits each of the numbered blanks from 25 to 29 Almost 90 percent of American students below the college level attend public elementary and secondary schools, which do not charge tuition but rely on local and state taxes for funding. Traditionally, elementary school includes kindergarten through the eighth grade. In some places (25) ________, elementary school ends after the sixth grade, and students attend middle school, or junior high school, from grades seven through nine. Similarly, secondary school, or high school, traditionally comprises grades nine through twelve, but in some places begins (26) ________ the tenth grade. Most of the students who do not attend public elementary and secondary schools attend private schools, for which their families pay (27) ________. Four out of five private schools are run by religious groups. In these schools, religious instruction is part of the curriculum, (28) _________ also includes the traditional academic courses. There is also a small but growing number of parents who educate their children themselves, a practice known as home schooling. The United States does not have a national school system. Nor, with the exception of the military academies, are there schools run by the federal government. But the government (29) _______ guidance and funding for federal educational programs in which both public and private schools take part, and the U.S. Department of Education oversees these programs
Read the following passage and mark the letter A, B, C, or D on your answer sheet to choose the word or phrase that best fits each of the numbered blanks from 25 to 29 Almost 90 percent of American students below the college level attend public elementary and secondary schools, which do not charge tuition but rely on local and state taxes for funding. Traditionally, elementary school includes kindergarten through the eighth grade. In some places (25) ________, elementary school ends after the sixth grade, and students attend middle school, or junior high school, from grades seven through nine. Similarly, secondary school, or high school, traditionally comprises grades nine through twelve, but in some places begins (26) ________ the tenth grade. Most of the students who do not attend public elementary and secondary schools attend private schools, for which their families pay (27) ________. Four out of five private schools are run by religious groups. In these schools, religious instruction is part of the curriculum, (28) _________ also includes the traditional academic courses. There is also a small but growing number of parents who educate their children themselves, a practice known as home schooling. The United States does not have a national school system. Nor, with the exception of the military academies, are there schools run by the federal government. But the government (29) _______ guidance and funding for federal educational programs in which both public and private schools take part, and the U.S. Department of Education oversees these programs
Read the following passage and mark the letter A, B, C, or D on your answer sheet to choose the word or phrase that best fits each of the numbered blanks from 25 to 29 Almost 90 percent of American students below the college level attend public elementary and secondary schools, which do not charge tuition but rely on local and state taxes for funding. Traditionally, elementary school includes kindergarten through the eighth grade. In some places (25) ________, elementary school ends after the sixth grade, and students attend middle school, or junior high school, from grades seven through nine. Similarly, secondary school, or high school, traditionally comprises grades nine through twelve, but in some places begins (26) ________ the tenth grade. Most of the students who do not attend public elementary and secondary schools attend private schools, for which their families pay (27) ________. Four out of five private schools are run by religious groups. In these schools, religious instruction is part of the curriculum, (28) _________ also includes the traditional academic courses. There is also a small but growing number of parents who educate their children themselves, a practice known as home schooling. The United States does not have a national school system. Nor, with the exception of the military academies, are there schools run by the federal government. But the government (29) _______ guidance and funding for federal educational programs in which both public and private schools take part, and the U.S. Department of Education oversees these programs
Read the following passage and mark the letter A, B, C, or D on your answer sheet to choose the word or phrase that best fits each of the numbered blanks from 25 to 29 Almost 90 percent of American students below the college level attend public elementary and secondary schools, which do not charge tuition but rely on local and state taxes for funding. Traditionally, elementary school includes kindergarten through the eighth grade. In some places (25) ________, elementary school ends after the sixth grade, and students attend middle school, or junior high school, from grades seven through nine. Similarly, secondary school, or high school, traditionally comprises grades nine through twelve, but in some places begins (26) ________ the tenth grade. Most of the students who do not attend public elementary and secondary schools attend private schools, for which their families pay (27) ________. Four out of five private schools are run by religious groups. In these schools, religious instruction is part of the curriculum, (28) _________ also includes the traditional academic courses. There is also a small but growing number of parents who educate their children themselves, a practice known as home schooling. The United States does not have a national school system. Nor, with the exception of the military academies, are there schools run by the federal government. But the government (29) _______ guidance and funding for federal educational programs in which both public and private schools take part, and the U.S. Department of Education oversees these programs
Read the following passage and mark the letter A, B, C, or D on your answer sheet to choose the word or phrase that best fits each of the numbered blanks from 25 to 29 Almost 90 percent of American students below the college level attend public elementary and secondary schools, which do not charge tuition but rely on local and state taxes for funding. Traditionally, elementary school includes kindergarten through the eighth grade. In some places (25) ________, elementary school ends after the sixth grade, and students attend middle school, or junior high school, from grades seven through nine. Similarly, secondary school, or high school, traditionally comprises grades nine through twelve, but in some places begins (26) ________ the tenth grade. Most of the students who do not attend public elementary and secondary schools attend private schools, for which their families pay (27) ________. Four out of five private schools are run by religious groups. In these schools, religious instruction is part of the curriculum, (28) _________ also includes the traditional academic courses. There is also a small but growing number of parents who educate their children themselves, a practice known as home schooling. The United States does not have a national school system. Nor, with the exception of the military academies, are there schools run by the federal government. But the government (29) _______ guidance and funding for federal educational programs in which both public and private schools take part, and the U.S. Department of Education oversees these programs
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 35 to 42       Scientists have discovered that for the last 160,000 years, at least, there has been a consistent relationship between the amount of carbon dioxide in the air and the average temperature of the planet. The importance of carbon dioxide in regulating the Earth's temperature was confirmed by scientists working in eastern Antarctica. Drilling down into a glacier, they extracted a mile-long cylinder of ice from the hole. The glacier had formed as layer upon layer of snow accumulated year after year. Thus, drilling into the ice was tantamount to drilling back through time.       The deepest sections of the core are composed of water that fell as snow 160,000 years ago. Scientists in Grenoble, France, fractured portions of the core and measured the composition of ancient air released from bubbles in the ice. Instruments were used to measure the ratio of certain isotopes in the frozen water to get an idea of the prevailing atmospheric temperature at the time when that particular bit of water became locked in the glacier.       The result is a remarkable unbroken record of temperature and of atmospheric levels of carbon dioxide. Almost every time the chill of an ice age descended on the planet, carbon dioxide levels dropped. When the global temperature dropped 9°F (5°C), carbon dioxide levels dropped to 190 parts per million or so. Generally, as each ice age ended and the Earth basked in a warm interglacial period, carbon dioxide levels were around 280 parts per million. Through the 160,000 years of that ice record, the level of carbon dioxide in the atmosphere fluctuated between 190 and 280 parts per million, but never rose much higher until the Industrial Revolution beginning in the eighteenth century and continuing today.            There is indirect evidence that the link between carbon dioxide levels and global temperature change goes back much further than the glacial record. Carbon dioxide levels may have been much greater than the current concentration during the Carboniferous period, 360 to 285 million years ago. The period was named for a profusion of plant life whose buried remains produced a large fraction of the coal deposits that are being brought to the surface and burned todayThe passage explains the origin of which of the following terms? 
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 35 to 42       Scientists have discovered that for the last 160,000 years, at least, there has been a consistent relationship between the amount of carbon dioxide in the air and the average temperature of the planet. The importance of carbon dioxide in regulating the Earth's temperature was confirmed by scientists working in eastern Antarctica. Drilling down into a glacier, they extracted a mile-long cylinder of ice from the hole. The glacier had formed as layer upon layer of snow accumulated year after year. Thus, drilling into the ice was tantamount to drilling back through time.       The deepest sections of the core are composed of water that fell as snow 160,000 years ago. Scientists in Grenoble, France, fractured portions of the core and measured the composition of ancient air released from bubbles in the ice. Instruments were used to measure the ratio of certain isotopes in the frozen water to get an idea of the prevailing atmospheric temperature at the time when that particular bit of water became locked in the glacier.       The result is a remarkable unbroken record of temperature and of atmospheric levels of carbon dioxide. Almost every time the chill of an ice age descended on the planet, carbon dioxide levels dropped. When the global temperature dropped 9°F (5°C), carbon dioxide levels dropped to 190 parts per million or so. Generally, as each ice age ended and the Earth basked in a warm interglacial period, carbon dioxide levels were around 280 parts per million. Through the 160,000 years of that ice record, the level of carbon dioxide in the atmosphere fluctuated between 190 and 280 parts per million, but never rose much higher until the Industrial Revolution beginning in the eighteenth century and continuing today.            There is indirect evidence that the link between carbon dioxide levels and global temperature change goes back much further than the glacial record. Carbon dioxide levels may have been much greater than the current concentration during the Carboniferous period, 360 to 285 million years ago. The period was named for a profusion of plant life whose buried remains produced a large fraction of the coal deposits that are being brought to the surface and burned todayAccording to the passage, the Carboniferous period was characterized by________
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 35 to 42       Scientists have discovered that for the last 160,000 years, at least, there has been a consistent relationship between the amount of carbon dioxide in the air and the average temperature of the planet. The importance of carbon dioxide in regulating the Earth's temperature was confirmed by scientists working in eastern Antarctica. Drilling down into a glacier, they extracted a mile-long cylinder of ice from the hole. The glacier had formed as layer upon layer of snow accumulated year after year. Thus, drilling into the ice was tantamount to drilling back through time.       The deepest sections of the core are composed of water that fell as snow 160,000 years ago. Scientists in Grenoble, France, fractured portions of the core and measured the composition of ancient air released from bubbles in the ice. Instruments were used to measure the ratio of certain isotopes in the frozen water to get an idea of the prevailing atmospheric temperature at the time when that particular bit of water became locked in the glacier.       The result is a remarkable unbroken record of temperature and of atmospheric levels of carbon dioxide. Almost every time the chill of an ice age descended on the planet, carbon dioxide levels dropped. When the global temperature dropped 9°F (5°C), carbon dioxide levels dropped to 190 parts per million or so. Generally, as each ice age ended and the Earth basked in a warm interglacial period, carbon dioxide levels were around 280 parts per million. Through the 160,000 years of that ice record, the level of carbon dioxide in the atmosphere fluctuated between 190 and 280 parts per million, but never rose much higher until the Industrial Revolution beginning in the eighteenth century and continuing today.            There is indirect evidence that the link between carbon dioxide levels and global temperature change goes back much further than the glacial record. Carbon dioxide levels may have been much greater than the current concentration during the Carboniferous period, 360 to 285 million years ago. The period was named for a profusion of plant life whose buried remains produced a large fraction of the coal deposits that are being brought to the surface and burned todayThe passage implies that the warmest temperatures among the periods mentioned occurred _______.  
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 35 to 42       Scientists have discovered that for the last 160,000 years, at least, there has been a consistent relationship between the amount of carbon dioxide in the air and the average temperature of the planet. The importance of carbon dioxide in regulating the Earth's temperature was confirmed by scientists working in eastern Antarctica. Drilling down into a glacier, they extracted a mile-long cylinder of ice from the hole. The glacier had formed as layer upon layer of snow accumulated year after year. Thus, drilling into the ice was tantamount to drilling back through time.       The deepest sections of the core are composed of water that fell as snow 160,000 years ago. Scientists in Grenoble, France, fractured portions of the core and measured the composition of ancient air released from bubbles in the ice. Instruments were used to measure the ratio of certain isotopes in the frozen water to get an idea of the prevailing atmospheric temperature at the time when that particular bit of water became locked in the glacier.       The result is a remarkable unbroken record of temperature and of atmospheric levels of carbon dioxide. Almost every time the chill of an ice age descended on the planet, carbon dioxide levels dropped. When the global temperature dropped 9°F (5°C), carbon dioxide levels dropped to 190 parts per million or so. Generally, as each ice age ended and the Earth basked in a warm interglacial period, carbon dioxide levels were around 280 parts per million. Through the 160,000 years of that ice record, the level of carbon dioxide in the atmosphere fluctuated between 190 and 280 parts per million, but never rose much higher until the Industrial Revolution beginning in the eighteenth century and continuing today.            There is indirect evidence that the link between carbon dioxide levels and global temperature change goes back much further than the glacial record. Carbon dioxide levels may have been much greater than the current concentration during the Carboniferous period, 360 to 285 million years ago. The period was named for a profusion of plant life whose buried remains produced a large fraction of the coal deposits that are being brought to the surface and burned todayThe word "remarkable" in line 12 is closest in meaning to _________.  
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 35 to 42       Scientists have discovered that for the last 160,000 years, at least, there has been a consistent relationship between the amount of carbon dioxide in the air and the average temperature of the planet. The importance of carbon dioxide in regulating the Earth's temperature was confirmed by scientists working in eastern Antarctica. Drilling down into a glacier, they extracted a mile-long cylinder of ice from the hole. The glacier had formed as layer upon layer of snow accumulated year after year. Thus, drilling into the ice was tantamount to drilling back through time.       The deepest sections of the core are composed of water that fell as snow 160,000 years ago. Scientists in Grenoble, France, fractured portions of the core and measured the composition of ancient air released from bubbles in the ice. Instruments were used to measure the ratio of certain isotopes in the frozen water to get an idea of the prevailing atmospheric temperature at the time when that particular bit of water became locked in the glacier.       The result is a remarkable unbroken record of temperature and of atmospheric levels of carbon dioxide. Almost every time the chill of an ice age descended on the planet, carbon dioxide levels dropped. When the global temperature dropped 9°F (5°C), carbon dioxide levels dropped to 190 parts per million or so. Generally, as each ice age ended and the Earth basked in a warm interglacial period, carbon dioxide levels were around 280 parts per million. Through the 160,000 years of that ice record, the level of carbon dioxide in the atmosphere fluctuated between 190 and 280 parts per million, but never rose much higher until the Industrial Revolution beginning in the eighteenth century and continuing today.            There is indirect evidence that the link between carbon dioxide levels and global temperature change goes back much further than the glacial record. Carbon dioxide levels may have been much greater than the current concentration during the Carboniferous period, 360 to 285 million years ago. The period was named for a profusion of plant life whose buried remains produced a large fraction of the coal deposits that are being brought to the surface and burned todayAccording to the passage, scientists used isotopes from the water of the ice core to determine which of following?  
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 35 to 42       Scientists have discovered that for the last 160,000 years, at least, there has been a consistent relationship between the amount of carbon dioxide in the air and the average temperature of the planet. The importance of carbon dioxide in regulating the Earth's temperature was confirmed by scientists working in eastern Antarctica. Drilling down into a glacier, they extracted a mile-long cylinder of ice from the hole. The glacier had formed as layer upon layer of snow accumulated year after year. Thus, drilling into the ice was tantamount to drilling back through time.       The deepest sections of the core are composed of water that fell as snow 160,000 years ago. Scientists in Grenoble, France, fractured portions of the core and measured the composition of ancient air released from bubbles in the ice. Instruments were used to measure the ratio of certain isotopes in the frozen water to get an idea of the prevailing atmospheric temperature at the time when that particular bit of water became locked in the glacier.       The result is a remarkable unbroken record of temperature and of atmospheric levels of carbon dioxide. Almost every time the chill of an ice age descended on the planet, carbon dioxide levels dropped. When the global temperature dropped 9°F (5°C), carbon dioxide levels dropped to 190 parts per million or so. Generally, as each ice age ended and the Earth basked in a warm interglacial period, carbon dioxide levels were around 280 parts per million. Through the 160,000 years of that ice record, the level of carbon dioxide in the atmosphere fluctuated between 190 and 280 parts per million, but never rose much higher until the Industrial Revolution beginning in the eighteenth century and continuing today.            There is indirect evidence that the link between carbon dioxide levels and global temperature change goes back much further than the glacial record. Carbon dioxide levels may have been much greater than the current concentration during the Carboniferous period, 360 to 285 million years ago. The period was named for a profusion of plant life whose buried remains produced a large fraction of the coal deposits that are being brought to the surface and burned todayThe phrase "tantamount to" in line 5 is closest in meaning to_______. 
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 35 to 42       Scientists have discovered that for the last 160,000 years, at least, there has been a consistent relationship between the amount of carbon dioxide in the air and the average temperature of the planet. The importance of carbon dioxide in regulating the Earth's temperature was confirmed by scientists working in eastern Antarctica. Drilling down into a glacier, they extracted a mile-long cylinder of ice from the hole. The glacier had formed as layer upon layer of snow accumulated year after year. Thus, drilling into the ice was tantamount to drilling back through time.       The deepest sections of the core are composed of water that fell as snow 160,000 years ago. Scientists in Grenoble, France, fractured portions of the core and measured the composition of ancient air released from bubbles in the ice. Instruments were used to measure the ratio of certain isotopes in the frozen water to get an idea of the prevailing atmospheric temperature at the time when that particular bit of water became locked in the glacier.       The result is a remarkable unbroken record of temperature and of atmospheric levels of carbon dioxide. Almost every time the chill of an ice age descended on the planet, carbon dioxide levels dropped. When the global temperature dropped 9°F (5°C), carbon dioxide levels dropped to 190 parts per million or so. Generally, as each ice age ended and the Earth basked in a warm interglacial period, carbon dioxide levels were around 280 parts per million. Through the 160,000 years of that ice record, the level of carbon dioxide in the atmosphere fluctuated between 190 and 280 parts per million, but never rose much higher until the Industrial Revolution beginning in the eighteenth century and continuing today.            There is indirect evidence that the link between carbon dioxide levels and global temperature change goes back much further than the glacial record. Carbon dioxide levels may have been much greater than the current concentration during the Carboniferous period, 360 to 285 million years ago. The period was named for a profusion of plant life whose buried remains produced a large fraction of the coal deposits that are being brought to the surface and burned todayAccording to the passage, the drilling of the glacier in eastern Antarctica was important because it ________ 
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 35 to 42       Scientists have discovered that for the last 160,000 years, at least, there has been a consistent relationship between the amount of carbon dioxide in the air and the average temperature of the planet. The importance of carbon dioxide in regulating the Earth's temperature was confirmed by scientists working in eastern Antarctica. Drilling down into a glacier, they extracted a mile-long cylinder of ice from the hole. The glacier had formed as layer upon layer of snow accumulated year after year. Thus, drilling into the ice was tantamount to drilling back through time.       The deepest sections of the core are composed of water that fell as snow 160,000 years ago. Scientists in Grenoble, France, fractured portions of the core and measured the composition of ancient air released from bubbles in the ice. Instruments were used to measure the ratio of certain isotopes in the frozen water to get an idea of the prevailing atmospheric temperature at the time when that particular bit of water became locked in the glacier.       The result is a remarkable unbroken record of temperature and of atmospheric levels of carbon dioxide. Almost every time the chill of an ice age descended on the planet, carbon dioxide levels dropped. When the global temperature dropped 9°F (5°C), carbon dioxide levels dropped to 190 parts per million or so. Generally, as each ice age ended and the Earth basked in a warm interglacial period, carbon dioxide levels were around 280 parts per million. Through the 160,000 years of that ice record, the level of carbon dioxide in the atmosphere fluctuated between 190 and 280 parts per million, but never rose much higher until the Industrial Revolution beginning in the eighteenth century and continuing today.            There is indirect evidence that the link between carbon dioxide levels and global temperature change goes back much further than the glacial record. Carbon dioxide levels may have been much greater than the current concentration during the Carboniferous period, 360 to 285 million years ago. The period was named for a profusion of plant life whose buried remains produced a large fraction of the coal deposits that are being brought to the surface and burned todayWhich of the following does the passage mainly discuss
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 30 to 34      As computer use becomes more common, the need for security is more common than ever. One of the greatest security threats in the online world is computer hacking.       Computer hacking is the unauthorized access to a computer or network of computers. Hackers are people who illegally enter systems. They may alter or delete information, steal private information, or spread viruses that can damage or destroy files. But how exactly can a hacker get into a system to do these things?       Most hackers use information called protocols that are built into computer software. These protocols allow computer to interact with one another. Protocols are sort of like computer police officers. When a computer connects to another system, the protocols check to see if the access is valid. The protocols can also determine how much information can be shared between the two systems. Hackers can manipulate the protocols to get unlimited access to a computer system.      In fact, just the act of entering a computer network is considered hacking. This is commonly called passive hacking. Passive hackers get a rush from just being able to access a challenging system like a bank or military network. Another kind of hacker tries to do damage to a system. After hacking into systems, these hackers release viruses or alter, delete, or take information. Known as active hackers, they are, by far, the more dangerous of the two.            The easiest way to protect a system is with a good password. Long and unusual passwords are harder for hackers to guess. For even greater security, some online services now use “password-plus” systems. In this case, users first put in a password and then put in a second code that changes after the user accesses the site. Users either have special cards or devices that show them the new code to use the next time. Even if a hacker steals the password, they won’t have the code. Or if the hacker somehow gets the code, they still don’t know the passwordWhat does “plus” in “password-plus” probably mean?