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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 28 to 34.Scientists do not yet thoroughly understand just how the body of an individual becomes sensitive to a substance that is harmless or even wholesome for the average person. Milk, wheat, and egg, for example, rank among the most healthful and widely used foods. Yet these foods can cause persons sensitive to them to suffer greatly. At first, the body of the individual is not harmed by coming into contact with the substance. After a varying interval of time, usually longer than a few weeks, the body becomes sensitive to it, and an allergy has begun to develop. Sometimes it’s hard to figure out if you have a food allergy, since it can show up so many different ways. Your symptoms could be caused by many other problems. You may have rashes, hives, joint pains mimicking arthritis, headaches, irritability, or depression. The most common food allergies are to milk, eggs, seafood, wheat, nuts, seeds, chocolate, oranges, and tomatoes. Many of these allergies will not develop if these foods are not fed to an infant until her or his intestines mature at around seven months. Breast milk also tends to be protective. Migraines can be set off by foods containing tyramine, phenathylamine, monosodium glutamate, or sodium nitrate. Common foods which contain these are chocolate, aged cheeses, sour cream, red wine, pickled herring, chicken livers, avocados, ripe bananas, cured meats, many Oriental and prepared foods (read the labels!). Some people have been successful in treating their migraines with supplements of B-vitamins, particularly B6 and niacin. Children who are hyperactive may benefit from eliminating food additives, especially colorings, and foods high in salicylates trom their diets.The topic of this passage is ____________.

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VIII/ Read the following passage on commuting, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 61 to 70.After two decades of growing student enrollments and economic prosperity , business schools in the United States have started to face harder times. Only Harvard’s MBA School has shown a substantial increase in enrollments in recent years. Both Princeton and Stanford have seen decreases in their enrollments. Since 1990, the number of people receiving Masters in Business Administration (MBA) degrees, has dropped about 3 percent to 75,000, and the trend of lower enrollment rates is expected to continue.There are two factors causing this decrease in students seeking an MBA degree. The first one is that many graduates of four-year colleges are finding that an MBA degree does not guarantee a plush job on Wall Street or in other financial districts of major American cities . Many of the entry-level management jobs are for students graduating with Master of Arts degrees in English and the humanities as well as those holding MBA degrees. Students have asked the question, “ Is an MBA degree really what I need to be best prepared for getting a good job?” The second major factor has been the cutting of American payrolls and the lower number of entry-level jobs being offered. Business needs are changing , and MBA schools are struggling to meet the new demands.What is the main focus of this passage?

Xem chi tiết 276 lượt xem 5 năm trước

Read the following passage on commuting, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 51 to 60.Many folk cures which have been around for centuries may be more therapeutic than previously suspected. A case in point is that of penicillin Alexander Fleming did not just randomly choose cheese molds to study when he discovered this very important bacteria-killing substance. Moldy cheese was frequently given to patients as a remedy for illness at one time Fleming just isolated what it was about the cheese which cured the patients.In parts of South America, a powder obtained from grinding sugar cane is used for healing infections in wounds and ulcers. This usage may date back to pre-Colombian times. Experiments carried out on several hundred patients indicate that ordinary sugar in high concentrations is lethal to bacteria. Its suction effect eliminates dead cells and it generates a glasslike layer which protects the wound and ensures healing.Another example of folk medicine which scientists are investigating is that of Arab fishermen who rub their wounds with a venomous catfish to quicken healing. This catfish excretes a gellike slime which scientist found to contain antibiotics coagulant that helps close injured blood vessels, anti-inflammatory agents, and a chemical that directs production of a glue-like material that aids healing.It is hoped that by documenting these folk remedies and experimenting to see if results are indeed beneficial, an analysis of the substance be made, and synthetic substances be developed for human consumption. The word "consumption" in the last paragraph is closest in meaning to_________.  

Xem chi tiết 284 lượt xem 5 năm trước

Read the following passage on commuting, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 51 to 60.Many folk cures which have been around for centuries may be more therapeutic than previously suspected. A case in point is that of penicillin Alexander Fleming did not just randomly choose cheese molds to study when he discovered this very important bacteria-killing substance. Moldy cheese was frequently given to patients as a remedy for illness at one time Fleming just isolated what it was about the cheese which cured the patients.In parts of South America, a powder obtained from grinding sugar cane is used for healing infections in wounds and ulcers. This usage may date back to pre-Colombian times. Experiments carried out on several hundred patients indicate that ordinary sugar in high concentrations is lethal to bacteria. Its suction effect eliminates dead cells and it generates a glasslike layer which protects the wound and ensures healing.Another example of folk medicine which scientists are investigating is that of Arab fishermen who rub their wounds with a venomous catfish to quicken healing. This catfish excretes a gellike slime which scientist found to contain antibiotics coagulant that helps close injured blood vessels, anti-inflammatory agents, and a chemical that directs production of a glue-like material that aids healing.It is hoped that by documenting these folk remedies and experimenting to see if results are indeed beneficial, an analysis of the substance be made, and synthetic substances be developed for human consumption. Which one of the following is NOT an important quality of the catfish slime?

Xem chi tiết 563 lượt xem 5 năm trước

Read the following passage on commuting, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 51 to 60.Many folk cures which have been around for centuries may be more therapeutic than previously suspected. A case in point is that of penicillin Alexander Fleming did not just randomly choose cheese molds to study when he discovered this very important bacteria-killing substance. Moldy cheese was frequently given to patients as a remedy for illness at one time Fleming just isolated what it was about the cheese which cured the patients.In parts of South America, a powder obtained from grinding sugar cane is used for healing infections in wounds and ulcers. This usage may date back to pre-Colombian times. Experiments carried out on several hundred patients indicate that ordinary sugar in high concentrations is lethal to bacteria. Its suction effect eliminates dead cells and it generates a glasslike layer which protects the wound and ensures healing.Another example of folk medicine which scientists are investigating is that of Arab fishermen who rub their wounds with a venomous catfish to quicken healing. This catfish excretes a gellike slime which scientist found to contain antibiotics coagulant that helps close injured blood vessels, anti-inflammatory agents, and a chemical that directs production of a glue-like material that aids healing.It is hoped that by documenting these folk remedies and experimenting to see if results are indeed beneficial, an analysis of the substance be made, and synthetic substances be developed for human consumption.The gellike substance which promotes healing comes from_________. 

Xem chi tiết 633 lượt xem 5 năm trước

 Read the following passage on commuting, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 51 to 60.Many folk cures which have been around for centuries may be more therapeutic than previously suspected. A case in point is that of penicillin Alexander Fleming did not just randomly choose cheese molds to study when he discovered this very important bacteria-killing substance. Moldy cheese was frequently given to patients as a remedy for illness at one time Fleming just isolated what it was about the cheese which cured the patients.In parts of South America, a powder obtained from grinding sugar cane is used for healing infections in wounds and ulcers. This usage may date back to pre-Colombian times. Experiments carried out on several hundred patients indicate that ordinary sugar in high concentrations is lethal to bacteria. Its suction effect eliminates dead cells and it generates a glasslike layer which protects the wound and ensures healing.Another example of folk medicine which scientists are investigating is that of Arab fishermen who rub their wounds with a venomous catfish to quicken healing. This catfish excretes a gellike slime which scientist found to contain antibiotics coagulant that helps close injured blood vessels, anti-inflammatory agents, and a chemical that directs production of a glue-like material that aids healing.It is hoped that by documenting these folk remedies and experimenting to see if results are indeed beneficial, an analysis of the substance be made, and synthetic substances be developed for human consumption. The word "eliminates" in paragraph 2 is closest in meaning to 

Xem chi tiết 421 lượt xem 5 năm trước

Read the following passage on commuting, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 51 to 60.Many folk cures which have been around for centuries may be more therapeutic than previously suspected. A case in point is that of penicillin Alexander Fleming did not just randomly choose cheese molds to study when he discovered this very important bacteria-killing substance. Moldy cheese was frequently given to patients as a remedy for illness at one time Fleming just isolated what it was about the cheese which cured the patients.In parts of South America, a powder obtained from grinding sugar cane is used for healing infections in wounds and ulcers. This usage may date back to pre-Colombian times. Experiments carried out on several hundred patients indicate that ordinary sugar in high concentrations is lethal to bacteria. Its suction effect eliminates dead cells and it generates a glasslike layer which protects the wound and ensures healing.Another example of folk medicine which scientists are investigating is that of Arab fishermen who rub their wounds with a venomous catfish to quicken healing. This catfish excretes a gellike slime which scientist found to contain antibiotics coagulant that helps close injured blood vessels, anti-inflammatory agents, and a chemical that directs production of a glue-like material that aids healing.It is hoped that by documenting these folk remedies and experimenting to see if results are indeed beneficial, an analysis of the substance be made, and synthetic substances be developed for human consumption. It can be inferred from the Message that Alexander Fleming_________.  

Xem chi tiết 0.9 K lượt xem 5 năm trước

Read the following passage on commuting, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 51 to 60.Many folk cures which have been around for centuries may be more therapeutic than previously suspected. A case in point is that of penicillin Alexander Fleming did not just randomly choose cheese molds to study when he discovered this very important bacteria-killing substance. Moldy cheese was frequently given to patients as a remedy for illness at one time Fleming just isolated what it was about the cheese which cured the patients.In parts of South America, a powder obtained from grinding sugar cane is used for healing infections in wounds and ulcers. This usage may date back to pre-Colombian times. Experiments carried out on several hundred patients indicate that ordinary sugar in high concentrations is lethal to bacteria. Its suction effect eliminates dead cells and it generates a glasslike layer which protects the wound and ensures healing.Another example of folk medicine which scientists are investigating is that of Arab fishermen who rub their wounds with a venomous catfish to quicken healing. This catfish excretes a gellike slime which scientist found to contain antibiotics coagulant that helps close injured blood vessels, anti-inflammatory agents, and a chemical that directs production of a glue-like material that aids healing.It is hoped that by documenting these folk remedies and experimenting to see if results are indeed beneficial, an analysis of the substance be made, and synthetic substances be developed for human consumption.This passage is mainly about_________.

Xem chi tiết 1.7 K lượt xem 5 năm trước

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.Herman Melville, an American author best known today for his novel Moby Dick, was actually more popular during his lifetime for some of his other works. He traveled extensively and used the knowledge gamed during his travels as the basis for his early novels. In 1837, at the age of eighteen, Melville slimed as a cabin boy on a merchant ship that was to sail from his Massachusetts home to Liverpool, England. His experiences on this trip served as a basis for the novel Redburn (1849). In 1841 Melville set out on a whaling ship headed for the South Seas. After jumping ship in Tahiti, he wandered around the islands of Tahiti and Moorea. This South Sea island sojourn was a backdrop to the novel Omoo (1847). After three years away from home, Melville joined up with a U.S. naval frigate that was returning to the eastern United States around Cape Horn. The novel White-Jacket (1850) describes this lengthy voyage as a navy seaman. With the publication of these early adventure novels, Melville developed a strong and loyal following among readers eager for his tales of exotic places and situations. However, in 1851, with the publication of Moby Dick, Melville's popularity started to diminish. Moby Dick, on one level the saga of the hunt for the great white whale, was also a heavily symbolic allegory of the heroic struggle of humanity against the universe. The public was not ready for Melville's literary metamorphosis from romantic adventure to philosophical symbolism. It is ironic that the novel that served to diminish Melville's popularity during his lifetime is the one for which he is best known today.The word "metamorphosis" is closest in meaning to_______ 

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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.Herman Melville, an American author best known today for his novel Moby Dick, was actually more popular during his lifetime for some of his other works. He traveled extensively and used the knowledge gamed during his travels as the basis for his early novels. In 1837, at the age of eighteen, Melville slimed as a cabin boy on a merchant ship that was to sail from his Massachusetts home to Liverpool, England. His experiences on this trip served as a basis for the novel Redburn (1849). In 1841 Melville set out on a whaling ship headed for the South Seas. After jumping ship in Tahiti, he wandered around the islands of Tahiti and Moorea. This South Sea island sojourn was a backdrop to the novel Omoo (1847). After three years away from home, Melville joined up with a U.S. naval frigate that was returning to the eastern United States around Cape Horn. The novel White-Jacket (1850) describes this lengthy voyage as a navy seaman. With the publication of these early adventure novels, Melville developed a strong and loyal following among readers eager for his tales of exotic places and situations. However, in 1851, with the publication of Moby Dick, Melville's popularity started to diminish. Moby Dick, on one level the saga of the hunt for the great white whale, was also a heavily symbolic allegory of the heroic struggle of humanity against the universe. The public was not ready for Melville's literary metamorphosis from romantic adventure to philosophical symbolism. It is ironic that the novel that served to diminish Melville's popularity during his lifetime is the one for which he is best known today.According to the passage, Moby Dick is_______ 

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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 44 to 50.Life originated in the early seas less than a billion years after Earth was formed. Yet another three billion years were to pass before the first plants and animals appeared on the continents. Life's transition from the sea to the land was perhaps as much of an evolutionary challenge as was the genesis of life.What forms of life were able to make such a drastic change in lifestyle? The traditional view of the first terrestrial organisms is based on mega fossils — relatively large specimens of essentially whole plants and animals. Vascular plants, related to modern seed plants and ferns, left the first comprehensive mega fossil record. Because of this, it has been commonly assumed that the sequence of terrestrialization reflected the evolution of modern terrestrial ecosystems. In this view, primitive vascular plants first colonized the margins of continental waters, followed by animals that fed on the plants, and lastly by animals that preyed on the plant-eaters. Moreover, the mega fossils suggest that terrestrial life appeared and diversified explosively near the boundary between the Silurian and the Devonian periods, a little more than 400 million years ago. Recently, however, paleontologists have been taking a closer look at the sediments below this Silurian-Devonian geological boundary. It turns out that some fossils can be extracted from these sediments by putting the rocks in an acid bath. The technique has uncovered new evidence from sediments that were deposited near the shores of the ancient oceans — plant microfossils and microscopic pieces of small animals. In many instances the specimens are less than one-tenth of a millimeter in diameter. Although they were entombed in the rocks for hundreds of millions of years, many of the fossils consist of the organic remains of the organism.These newly discovered fossils have not only revealed the existence of previously unknown organisms, but have also pushed back these dates for the invasion of land by multicellular organisms. Our views about the nature of the early plant and animal communities are now being revised. And with those revisions come new speculations about the first terrestrial life-forms.With which of the following conclusions would the author probably agree?

Xem chi tiết 323 lượt xem 5 năm trước

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 44 to 50.Life originated in the early seas less than a billion years after Earth was formed. Yet another three billion years were to pass before the first plants and animals appeared on the continents. Life's transition from the sea to the land was perhaps as much of an evolutionary challenge as was the genesis of life.What forms of life were able to make such a drastic change in lifestyle? The traditional view of the first terrestrial organisms is based on mega fossils — relatively large specimens of essentially whole plants and animals. Vascular plants, related to modern seed plants and ferns, left the first comprehensive mega fossil record. Because of this, it has been commonly assumed that the sequence of terrestrialization reflected the evolution of modern terrestrial ecosystems. In this view, primitive vascular plants first colonized the margins of continental waters, followed by animals that fed on the plants, and lastly by animals that preyed on the plant-eaters. Moreover, the mega fossils suggest that terrestrial life appeared and diversified explosively near the boundary between the Silurian and the Devonian periods, a little more than 400 million years ago. Recently, however, paleontologists have been taking a closer look at the sediments below this Silurian-Devonian geological boundary. It turns out that some fossils can be extracted from these sediments by putting the rocks in an acid bath. The technique has uncovered new evidence from sediments that were deposited near the shores of the ancient oceans — plant microfossils and microscopic pieces of small animals. In many instances the specimens are less than one-tenth of a millimeter in diameter. Although they were entombed in the rocks for hundreds of millions of years, many of the fossils consist of the organic remains of the organism.These newly discovered fossils have not only revealed the existence of previously unknown organisms, but have also pushed back these dates for the invasion of land by multicellular organisms. Our views about the nature of the early plant and animal communities are now being revised. And with those revisions come new speculations about the first terrestrial life-forms.Which of the following resulted from the discovery of microscopic fossils?

Xem chi tiết 1.6 K lượt xem 5 năm trước

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 44 to 50.Life originated in the early seas less than a billion years after Earth was formed. Yet another three billion years were to pass before the first plants and animals appeared on the continents. Life's transition from the sea to the land was perhaps as much of an evolutionary challenge as was the genesis of life.What forms of life were able to make such a drastic change in lifestyle? The traditional view of the first terrestrial organisms is based on mega fossils — relatively large specimens of essentially whole plants and animals. Vascular plants, related to modern seed plants and ferns, left the first comprehensive mega fossil record. Because of this, it has been commonly assumed that the sequence of terrestrialization reflected the evolution of modern terrestrial ecosystems. In this view, primitive vascular plants first colonized the margins of continental waters, followed by animals that fed on the plants, and lastly by animals that preyed on the plant-eaters. Moreover, the mega fossils suggest that terrestrial life appeared and diversified explosively near the boundary between the Silurian and the Devonian periods, a little more than 400 million years ago. Recently, however, paleontologists have been taking a closer look at the sediments below this Silurian-Devonian geological boundary. It turns out that some fossils can be extracted from these sediments by putting the rocks in an acid bath. The technique has uncovered new evidence from sediments that were deposited near the shores of the ancient oceans — plant microfossils and microscopic pieces of small animals. In many instances the specimens are less than one-tenth of a millimeter in diameter. Although they were entombed in the rocks for hundreds of millions of years, many of the fossils consist of the organic remains of the organism.These newly discovered fossils have not only revealed the existence of previously unknown organisms, but have also pushed back these dates for the invasion of land by multicellular organisms. Our views about the nature of the early plant and animal communities are now being revised. And with those revisions come new speculations about the first terrestrial life-forms.The word “entombed” in lime 22 is closest in meaning to

Xem chi tiết 334 lượt xem 5 năm trước

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 44 to 50.Life originated in the early seas less than a billion years after Earth was formed. Yet another three billion years were to pass before the first plants and animals appeared on the continents. Life's transition from the sea to the land was perhaps as much of an evolutionary challenge as was the genesis of life.What forms of life were able to make such a drastic change in lifestyle? The traditional view of the first terrestrial organisms is based on mega fossils — relatively large specimens of essentially whole plants and animals. Vascular plants, related to modern seed plants and ferns, left the first comprehensive mega fossil record. Because of this, it has been commonly assumed that the sequence of terrestrialization reflected the evolution of modern terrestrial ecosystems. In this view, primitive vascular plants first colonized the margins of continental waters, followed by animals that fed on the plants, and lastly by animals that preyed on the plant-eaters. Moreover, the mega fossils suggest that terrestrial life appeared and diversified explosively near the boundary between the Silurian and the Devonian periods, a little more than 400 million years ago. Recently, however, paleontologists have been taking a closer look at the sediments below this Silurian-Devonian geological boundary. It turns out that some fossils can be extracted from these sediments by putting the rocks in an acid bath. The technique has uncovered new evidence from sediments that were deposited near the shores of the ancient oceans — plant microfossils and microscopic pieces of small animals. In many instances the specimens are less than one-tenth of a millimeter in diameter. Although they were entombed in the rocks for hundreds of millions of years, many of the fossils consist of the organic remains of the organism.These newly discovered fossils have not only revealed the existence of previously unknown organisms, but have also pushed back these dates for the invasion of land by multicellular organisms. Our views about the nature of the early plant and animal communities are now being revised. And with those revisions come new speculations about the first terrestrial life-forms.The word “they” in line 22 refers to

Xem chi tiết 1.2 K lượt xem 5 năm trước

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 44 to 50.Life originated in the early seas less than a billion years after Earth was formed. Yet another three billion years were to pass before the first plants and animals appeared on the continents. Life's transition from the sea to the land was perhaps as much of an evolutionary challenge as was the genesis of life.What forms of life were able to make such a drastic change in lifestyle? The traditional view of the first terrestrial organisms is based on mega fossils — relatively large specimens of essentially whole plants and animals. Vascular plants, related to modern seed plants and ferns, left the first comprehensive mega fossil record. Because of this, it has been commonly assumed that the sequence of terrestrialization reflected the evolution of modern terrestrial ecosystems. In this view, primitive vascular plants first colonized the margins of continental waters, followed by animals that fed on the plants, and lastly by animals that preyed on the plant-eaters. Moreover, the mega fossils suggest that terrestrial life appeared and diversified explosively near the boundary between the Silurian and the Devonian periods, a little more than 400 million years ago. Recently, however, paleontologists have been taking a closer look at the sediments below this Silurian-Devonian geological boundary. It turns out that some fossils can be extracted from these sediments by putting the rocks in an acid bath. The technique has uncovered new evidence from sediments that were deposited near the shores of the ancient oceans — plant microfossils and microscopic pieces of small animals. In many instances the specimens are less than one-tenth of a millimeter in diameter. Although they were entombed in the rocks for hundreds of millions of years, many of the fossils consist of the organic remains of the organism.These newly discovered fossils have not only revealed the existence of previously unknown organisms, but have also pushed back these dates for the invasion of land by multicellular organisms. Our views about the nature of the early plant and animal communities are now being revised. And with those revisions come new speculations about the first terrestrial life-forms.What can be inferred from the passage about the fossils mentioned in lines 17-20?

Xem chi tiết 1.2 K lượt xem 5 năm trước

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 44 to 50.Life originated in the early seas less than a billion years after Earth was formed. Yet another three billion years were to pass before the first plants and animals appeared on the continents. Life's transition from the sea to the land was perhaps as much of an evolutionary challenge as was the genesis of life.What forms of life were able to make such a drastic change in lifestyle? The traditional view of the first terrestrial organisms is based on mega fossils — relatively large specimens of essentially whole plants and animals. Vascular plants, related to modern seed plants and ferns, left the first comprehensive mega fossil record. Because of this, it has been commonly assumed that the sequence of terrestrialization reflected the evolution of modern terrestrial ecosystems. In this view, primitive vascular plants first colonized the margins of continental waters, followed by animals that fed on the plants, and lastly by animals that preyed on the plant-eaters. Moreover, the mega fossils suggest that terrestrial life appeared and diversified explosively near the boundary between the Silurian and the Devonian periods, a little more than 400 million years ago. Recently, however, paleontologists have been taking a closer look at the sediments below this Silurian-Devonian geological boundary. It turns out that some fossils can be extracted from these sediments by putting the rocks in an acid bath. The technique has uncovered new evidence from sediments that were deposited near the shores of the ancient oceans — plant microfossils and microscopic pieces of small animals. In many instances the specimens are less than one-tenth of a millimeter in diameter. Although they were entombed in the rocks for hundreds of millions of years, many of the fossils consist of the organic remains of the organism.These newly discovered fossils have not only revealed the existence of previously unknown organisms, but have also pushed back these dates for the invasion of land by multicellular organisms. Our views about the nature of the early plant and animal communities are now being revised. And with those revisions come new speculations about the first terrestrial life-forms.According to the passage, what happened about 400 million years ago?

Xem chi tiết 814 lượt xem 5 năm trước

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 44 to 50.Life originated in the early seas less than a billion years after Earth was formed. Yet another three billion years were to pass before the first plants and animals appeared on the continents. Life's transition from the sea to the land was perhaps as much of an evolutionary challenge as was the genesis of life.What forms of life were able to make such a drastic change in lifestyle? The traditional view of the first terrestrial organisms is based on mega fossils — relatively large specimens of essentially whole plants and animals. Vascular plants, related to modern seed plants and ferns, left the first comprehensive mega fossil record. Because of this, it has been commonly assumed that the sequence of terrestrialization reflected the evolution of modern terrestrial ecosystems. In this view, primitive vascular plants first colonized the margins of continental waters, followed by animals that fed on the plants, and lastly by animals that preyed on the plant-eaters. Moreover, the mega fossils suggest that terrestrial life appeared and diversified explosively near the boundary between the Silurian and the Devonian periods, a little more than 400 million years ago. Recently, however, paleontologists have been taking a closer look at the sediments below this Silurian-Devonian geological boundary. It turns out that some fossils can be extracted from these sediments by putting the rocks in an acid bath. The technique has uncovered new evidence from sediments that were deposited near the shores of the ancient oceans — plant microfossils and microscopic pieces of small animals. In many instances the specimens are less than one-tenth of a millimeter in diameter. Although they were entombed in the rocks for hundreds of millions of years, many of the fossils consist of the organic remains of the organism.These newly discovered fossils have not only revealed the existence of previously unknown organisms, but have also pushed back these dates for the invasion of land by multicellular organisms. Our views about the nature of the early plant and animal communities are now being revised. And with those revisions come new speculations about the first terrestrial life-forms.According to the theory that the author calls “the traditional view,” what was the first form of life to appear on land?

Xem chi tiết 321 lượt xem 5 năm trước

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 44 to 50.Life originated in the early seas less than a billion years after Earth was formed. Yet another three billion years were to pass before the first plants and animals appeared on the continents. Life's transition from the sea to the land was perhaps as much of an evolutionary challenge as was the genesis of life.What forms of life were able to make such a drastic change in lifestyle? The traditional view of the first terrestrial organisms is based on mega fossils — relatively large specimens of essentially whole plants and animals. Vascular plants, related to modern seed plants and ferns, left the first comprehensive mega fossil record. Because of this, it has been commonly assumed that the sequence of terrestrialization reflected the evolution of modern terrestrial ecosystems. In this view, primitive vascular plants first colonized the margins of continental waters, followed by animals that fed on the plants, and lastly by animals that preyed on the plant-eaters. Moreover, the mega fossils suggest that terrestrial life appeared and diversified explosively near the boundary between the Silurian and the Devonian periods, a little more than 400 million years ago. Recently, however, paleontologists have been taking a closer look at the sediments below this Silurian-Devonian geological boundary. It turns out that some fossils can be extracted from these sediments by putting the rocks in an acid bath. The technique has uncovered new evidence from sediments that were deposited near the shores of the ancient oceans — plant microfossils and microscopic pieces of small animals. In many instances the specimens are less than one-tenth of a millimeter in diameter. Although they were entombed in the rocks for hundreds of millions of years, many of the fossils consist of the organic remains of the organism.These newly discovered fossils have not only revealed the existence of previously unknown organisms, but have also pushed back these dates for the invasion of land by multicellular organisms. Our views about the nature of the early plant and animal communities are now being revised. And with those revisions come new speculations about the first terrestrial life-forms. The word “drastic” in line 5 is closest in meaning to

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