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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 31 to 35.We're always being urged to stay safe online. But in an era where the internet is part of our everyday lives - for work, fun, study, shopping, even managing finances - it's not always easy to spot the dangers. Web safety expert, Amanda Knox, explores some of the issues lurking in cyberspace.Her first piece of advice is to install software and a firewall to protect your computer from viruses, hackers and criminals who want to steal your data or financial information. "Think of these as your first line of defense," says Amanda.So much for protecting yourself against intruders, but what about other problems? Say you've accidentally deleted an important file or you've been at the mercy of a natural disaster. Katy Marsh runs an online photography business from home and when a fire destroyed part of her house it could easily have spelled ruin for her business too. "Luckily I keep a regular back-up of my data so it wasn't a catastrophe."Whilst most of us are aware of the need to protect our computers, it seems we're more lax when it comes to looking out for ourselves, at least according to a recent web awareness survey. Web safety specialists say better personal awareness is needed and this is due in part to the rise of 'Social Networking' sites like 'Bebo', 'MySpace' and 'Facebook', which allow us to connect with people around the world with similar interests and professional backgrounds.This brings us to other potential pitfalls. Are the people you meet online who they really claim to be? Can you be sure the person you're chatting with is in fact a 22-year-old Maths undergraduate from London and not someone merely masquerading as a student to win your trust?When networking and joining online communities it's better to be cautious about the amount of personal information you share. For example, it isn't always necessary to use your real name as a username when registering for a service. You could instead use a pseudonym, or a name that doesn't give away your real identity to other users. And is it really important to tell the world details about your school, college or any local clubs you're a member of?If you do experience problems from another user be prepared to report them for misusing the service. You'll be doing other users a favour too. And if all else fails, check to see if it is easy to delete your account and leave the service if you choose to and that you have the option to delete all your details.A general rule of thumb is not to post any information about yourself that you would not be happy for the world to know - not just now but in years to come. This includes photographs of yourself, particularly embarrassing shots of you at that party which you may later regret! It's not always easy to remove information after it's been posted so you - not to mention your future employer - may have an unpleasant surprise a few years down the line.The effect of the fire was______________.
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 26 to 30.Is organic food safer and more (26) ______________                   ? This is an important part of the debate.Many farmers and consumers believe it is. They think agricultural chemicals can cause serious illnesses like cancer, but there isn't much evidence proving this is true. However, recent studies have shown that eating organically-grown produce (27) ______________your chances of developing heart disease. Many doctors think it's more important to stop dangerous bacteria from contaminating foods. These bacteria can contaminate both organic and non-organic fruit and vegetables, and doctors recommend washing them carefully before eating them. Meat, fish and chicken can also become contaminated, so washing your hands before handling these foods is also very important. Many doctors also believe we should reduce the amount of sugar in our diets, and there is a lot of evidence to support this idea. They recommend carefully checking the list of ingredients on processed food and drinks for all the words that really mean sugar, like glucose, sucrose and fructose. And they remind us that the aim of most big food companies is (28) ______________lots of money, even if they damage our health while doing so. This means processed foods that are called "organic" can also be very (29) ______________if they contain lots of sugar.Most people agree that naturally grown food tastes better. Is tastier food worth the extra money? That's a matter of opinion. Whether organic food is healthier or not is still not clear, (30) ______________more research is needed. However, consumers of organic food often say "better safe than sorry" when it comes to what we eat
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 26 to 30.Is organic food safer and more (26) ______________                   ? This is an important part of the debate.Many farmers and consumers believe it is. They think agricultural chemicals can cause serious illnesses like cancer, but there isn't much evidence proving this is true. However, recent studies have shown that eating organically-grown produce (27) ______________your chances of developing heart disease. Many doctors think it's more important to stop dangerous bacteria from contaminating foods. These bacteria can contaminate both organic and non-organic fruit and vegetables, and doctors recommend washing them carefully before eating them. Meat, fish and chicken can also become contaminated, so washing your hands before handling these foods is also very important. Many doctors also believe we should reduce the amount of sugar in our diets, and there is a lot of evidence to support this idea. They recommend carefully checking the list of ingredients on processed food and drinks for all the words that really mean sugar, like glucose, sucrose and fructose. And they remind us that the aim of most big food companies is (28) ______________lots of money, even if they damage our health while doing so. This means processed foods that are called "organic" can also be very (29) ______________if they contain lots of sugar.Most people agree that naturally grown food tastes better. Is tastier food worth the extra money? That's a matter of opinion. Whether organic food is healthier or not is still not clear, (30) ______________more research is needed. However, consumers of organic food often say "better safe than sorry" when it comes to what we eat.
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 26 to 30.Is organic food safer and more (26) ______________                   ? This is an important part of the debate.Many farmers and consumers believe it is. They think agricultural chemicals can cause serious illnesses like cancer, but there isn't much evidence proving this is true. However, recent studies have shown that eating organically-grown produce (27) ______________your chances of developing heart disease. Many doctors think it's more important to stop dangerous bacteria from contaminating foods. These bacteria can contaminate both organic and non-organic fruit and vegetables, and doctors recommend washing them carefully before eating them. Meat, fish and chicken can also become contaminated, so washing your hands before handling these foods is also very important. Many doctors also believe we should reduce the amount of sugar in our diets, and there is a lot of evidence to support this idea. They recommend carefully checking the list of ingredients on processed food and drinks for all the words that really mean sugar, like glucose, sucrose and fructose. And they remind us that the aim of most big food companies is (28) ______________lots of money, even if they damage our health while doing so. This means processed foods that are called "organic" can also be very (29) ______________if they contain lots of sugar.Most people agree that naturally grown food tastes better. Is tastier food worth the extra money? That's a matter of opinion. Whether organic food is healthier or not is still not clear, (30) ______________more research is needed. However, consumers of organic food often say "better safe than sorry" when it comes to what we eat.
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 26 to 30.Is organic food safer and more (26) ______________                   ? This is an important part of the debate.Many farmers and consumers believe it is. They think agricultural chemicals can cause serious illnesses like cancer, but there isn't much evidence proving this is true. However, recent studies have shown that eating organically-grown produce (27) ______________your chances of developing heart disease. Many doctors think it's more important to stop dangerous bacteria from contaminating foods. These bacteria can contaminate both organic and non-organic fruit and vegetables, and doctors recommend washing them carefully before eating them. Meat, fish and chicken can also become contaminated, so washing your hands before handling these foods is also very important. Many doctors also believe we should reduce the amount of sugar in our diets, and there is a lot of evidence to support this idea. They recommend carefully checking the list of ingredients on processed food and drinks for all the words that really mean sugar, like glucose, sucrose and fructose. And they remind us that the aim of most big food companies is (28) ______________lots of money, even if they damage our health while doing so. This means processed foods that are called "organic" can also be very (29) ______________if they contain lots of sugar.Most people agree that naturally grown food tastes better. Is tastier food worth the extra money? That's a matter of opinion. Whether organic food is healthier or not is still not clear, (30) ______________more research is needed. However, consumers of organic food often say "better safe than sorry" when it comes to what we eat.
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 26 to 30.Is organic food safer and more (26) ______________                   ? This is an important part of the debate.Many farmers and consumers believe it is. They think agricultural chemicals can cause serious illnesses like cancer, but there isn't much evidence proving this is true. However, recent studies have shown that eating organically-grown produce (27) ______________your chances of developing heart disease. Many doctors think it's more important to stop dangerous bacteria from contaminating foods. These bacteria can contaminate both organic and non-organic fruit and vegetables, and doctors recommend washing them carefully before eating them. Meat, fish and chicken can also become contaminated, so washing your hands before handling these foods is also very important. Many doctors also believe we should reduce the amount of sugar in our diets, and there is a lot of evidence to support this idea. They recommend carefully checking the list of ingredients on processed food and drinks for all the words that really mean sugar, like glucose, sucrose and fructose. And they remind us that the aim of most big food companies is (28) ______________lots of money, even if they damage our health while doing so. This means processed foods that are called "organic" can also be very (29) ______________if they contain lots of sugar.Most people agree that naturally grown food tastes better. Is tastier food worth the extra money? That's a matter of opinion. Whether organic food is healthier or not is still not clear, (30) ______________more research is needed. However, consumers of organic food often say "better safe than sorry" when it comes to what we eat.
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 36 to 42The Native Americans of northern California were very good at basketry, using the reeds, grasses, barks, and roots they found around them to fashion articles of all sorts and sizes - not only trays, containers, and cooking pots, but hats, boats, fish traps, baby carriers, and ceremonial objects.Of all these experts, none excelled the Porno - a group who lived on or near the coast during the 1800's, and whose descendants continue to live in parts of the same region to this day. They made baskets three feet in diameter and others no bigger than a thimble. The Pomo people were masters of decoration. Some of their baskets were completely covered with shell pendants; others with feathers that made the baskets' surfaces as soft as the breasts of birds. Moreover, the Pomo people made use of more weaving techniques than did their neighbors. Most groups made all their basketwork by twining - the twisting of a flexible horizontal material, called a weft, around stiffer vertical strands of material, the warp, others depended primarily on coiling - a process in which a continuous coil of stiff material is held in the desired shape with tight wrapping of flexible strands. Only the Pomo people used both processes with equal ease and frequency. In addition, they made use of four distinct variations on the basic twining process, often employing more than one of them in a single article.Although a wide variety of materials was available, the Pomo people used only a few. The warp was always made of willow, and the most commonly used weft was sedge root, a woody fiber that could easily be separated into strands no thicker than a thread. For color, the Pomo people used the bark of redbud for their twined work and dyed bulrush root for black in coiled work. Though other materials were sometimes used, these four were the staples in their finest basketry.If the basketry materials used by the Pomo people were limited, the designs were amazingly varied. Every Pomo basketmaker knew how to produce from fifteen to twenty distinct patterns that could be combined in a number of different ways.Which of the following statements about Pomo baskets can be best inferred from the passage?
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 36 to 42The Native Americans of northern California were very good at basketry, using the reeds, grasses, barks, and roots they found around them to fashion articles of all sorts and sizes - not only trays, containers, and cooking pots, but hats, boats, fish traps, baby carriers, and ceremonial objects.Of all these experts, none excelled the Porno - a group who lived on or near the coast during the 1800's, and whose descendants continue to live in parts of the same region to this day. They made baskets three feet in diameter and others no bigger than a thimble. The Pomo people were masters of decoration. Some of their baskets were completely covered with shell pendants; others with feathers that made the baskets' surfaces as soft as the breasts of birds. Moreover, the Pomo people made use of more weaving techniques than did their neighbors. Most groups made all their basketwork by twining - the twisting of a flexible horizontal material, called a weft, around stiffer vertical strands of material, the warp, others depended primarily on coiling - a process in which a continuous coil of stiff material is held in the desired shape with tight wrapping of flexible strands. Only the Pomo people used both processes with equal ease and frequency. In addition, they made use of four distinct variations on the basic twining process, often employing more than one of them in a single article.Although a wide variety of materials was available, the Pomo people used only a few. The warp was always made of willow, and the most commonly used weft was sedge root, a woody fiber that could easily be separated into strands no thicker than a thread. For color, the Pomo people used the bark of redbud for their twined work and dyed bulrush root for black in coiled work. Though other materials were sometimes used, these four were the staples in their finest basketry.If the basketry materials used by the Pomo people were limited, the designs were amazingly varied. Every Pomo basketmaker knew how to produce from fifteen to twenty distinct patterns that could be combined in a number of different ways.The word "staples" in line 21 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 36 to 42The Native Americans of northern California were very good at basketry, using the reeds, grasses, barks, and roots they found around them to fashion articles of all sorts and sizes - not only trays, containers, and cooking pots, but hats, boats, fish traps, baby carriers, and ceremonial objects.Of all these experts, none excelled the Porno - a group who lived on or near the coast during the 1800's, and whose descendants continue to live in parts of the same region to this day. They made baskets three feet in diameter and others no bigger than a thimble. The Pomo people were masters of decoration. Some of their baskets were completely covered with shell pendants; others with feathers that made the baskets' surfaces as soft as the breasts of birds. Moreover, the Pomo people made use of more weaving techniques than did their neighbors. Most groups made all their basketwork by twining - the twisting of a flexible horizontal material, called a weft, around stiffer vertical strands of material, the warp, others depended primarily on coiling - a process in which a continuous coil of stiff material is held in the desired shape with tight wrapping of flexible strands. Only the Pomo people used both processes with equal ease and frequency. In addition, they made use of four distinct variations on the basic twining process, often employing more than one of them in a single article.Although a wide variety of materials was available, the Pomo people used only a few. The warp was always made of willow, and the most commonly used weft was sedge root, a woody fiber that could easily be separated into strands no thicker than a thread. For color, the Pomo people used the bark of redbud for their twined work and dyed bulrush root for black in coiled work. Though other materials were sometimes used, these four were the staples in their finest basketry.If the basketry materials used by the Pomo people were limited, the designs were amazingly varied. Every Pomo basketmaker knew how to produce from fifteen to twenty distinct patterns that could be combined in a number of different ways.According to the passage, what did the Pomo people use as the warp in their baskets?
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 36 to 42The Native Americans of northern California were very good at basketry, using the reeds, grasses, barks, and roots they found around them to fashion articles of all sorts and sizes - not only trays, containers, and cooking pots, but hats, boats, fish traps, baby carriers, and ceremonial objects.Of all these experts, none excelled the Porno - a group who lived on or near the coast during the 1800's, and whose descendants continue to live in parts of the same region to this day. They made baskets three feet in diameter and others no bigger than a thimble. The Pomo people were masters of decoration. Some of their baskets were completely covered with shell pendants; others with feathers that made the baskets' surfaces as soft as the breasts of birds. Moreover, the Pomo people made use of more weaving techniques than did their neighbors. Most groups made all their basketwork by twining - the twisting of a flexible horizontal material, called a weft, around stiffer vertical strands of material, the warp, others depended primarily on coiling - a process in which a continuous coil of stiff material is held in the desired shape with tight wrapping of flexible strands. Only the Pomo people used both processes with equal ease and frequency. In addition, they made use of four distinct variations on the basic twining process, often employing more than one of them in a single article.Although a wide variety of materials was available, the Pomo people used only a few. The warp was always made of willow, and the most commonly used weft was sedge root, a woody fiber that could easily be separated into strands no thicker than a thread. For color, the Pomo people used the bark of redbud for their twined work and dyed bulrush root for black in coiled work. Though other materials were sometimes used, these four were the staples in their finest basketry.If the basketry materials used by the Pomo people were limited, the designs were amazingly varied. Every Pomo basketmaker knew how to produce from fifteen to twenty distinct patterns that could be combined in a number of different ways.According to the passage, a weft is a____________.
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 36 to 42The Native Americans of northern California were very good at basketry, using the reeds, grasses, barks, and roots they found around them to fashion articles of all sorts and sizes - not only trays, containers, and cooking pots, but hats, boats, fish traps, baby carriers, and ceremonial objects.Of all these experts, none excelled the Porno - a group who lived on or near the coast during the 1800's, and whose descendants continue to live in parts of the same region to this day. They made baskets three feet in diameter and others no bigger than a thimble. The Pomo people were masters of decoration. Some of their baskets were completely covered with shell pendants; others with feathers that made the baskets' surfaces as soft as the breasts of birds. Moreover, the Pomo people made use of more weaving techniques than did their neighbors. Most groups made all their basketwork by twining - the twisting of a flexible horizontal material, called a weft, around stiffer vertical strands of material, the warp, others depended primarily on coiling - a process in which a continuous coil of stiff material is held in the desired shape with tight wrapping of flexible strands. Only the Pomo people used both processes with equal ease and frequency. In addition, they made use of four distinct variations on the basic twining process, often employing more than one of them in a single article.Although a wide variety of materials was available, the Pomo people used only a few. The warp was always made of willow, and the most commonly used weft was sedge root, a woody fiber that could easily be separated into strands no thicker than a thread. For color, the Pomo people used the bark of redbud for their twined work and dyed bulrush root for black in coiled work. Though other materials were sometimes used, these four were the staples in their finest basketry.If the basketry materials used by the Pomo people were limited, the designs were amazingly varied. Every Pomo basketmaker knew how to produce from fifteen to twenty distinct patterns that could be combined in a number of different ways.What is the author's main point in the second paragraph?
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 36 to 42The Native Americans of northern California were very good at basketry, using the reeds, grasses, barks, and roots they found around them to fashion articles of all sorts and sizes - not only trays, containers, and cooking pots, but hats, boats, fish traps, baby carriers, and ceremonial objects.Of all these experts, none excelled the Porno - a group who lived on or near the coast during the 1800's, and whose descendants continue to live in parts of the same region to this day. They made baskets three feet in diameter and others no bigger than a thimble. The Pomo people were masters of decoration. Some of their baskets were completely covered with shell pendants; others with feathers that made the baskets' surfaces as soft as the breasts of birds. Moreover, the Pomo people made use of more weaving techniques than did their neighbors. Most groups made all their basketwork by twining - the twisting of a flexible horizontal material, called a weft, around stiffer vertical strands of material, the warp, others depended primarily on coiling - a process in which a continuous coil of stiff material is held in the desired shape with tight wrapping of flexible strands. Only the Pomo people used both processes with equal ease and frequency. In addition, they made use of four distinct variations on the basic twining process, often employing more than one of them in a single article.Although a wide variety of materials was available, the Pomo people used only a few. The warp was always made of willow, and the most commonly used weft was sedge root, a woody fiber that could easily be separated into strands no thicker than a thread. For color, the Pomo people used the bark of redbud for their twined work and dyed bulrush root for black in coiled work. Though other materials were sometimes used, these four were the staples in their finest basketry.If the basketry materials used by the Pomo people were limited, the designs were amazingly varied. Every Pomo basketmaker knew how to produce from fifteen to twenty distinct patterns that could be combined in a number of different ways.The Pomo people used each of the following materials to decorate baskets EXCEPT____________.
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 36 to 42The Native Americans of northern California were very good at basketry, using the reeds, grasses, barks, and roots they found around them to fashion articles of all sorts and sizes - not only trays, containers, and cooking pots, but hats, boats, fish traps, baby carriers, and ceremonial objects.Of all these experts, none excelled the Porno - a group who lived on or near the coast during the 1800's, and whose descendants continue to live in parts of the same region to this day. They made baskets three feet in diameter and others no bigger than a thimble. The Pomo people were masters of decoration. Some of their baskets were completely covered with shell pendants; others with feathers that made the baskets' surfaces as soft as the breasts of birds. Moreover, the Pomo people made use of more weaving techniques than did their neighbors. Most groups made all their basketwork by twining - the twisting of a flexible horizontal material, called a weft, around stiffer vertical strands of material, the warp, others depended primarily on coiling - a process in which a continuous coil of stiff material is held in the desired shape with tight wrapping of flexible strands. Only the Pomo people used both processes with equal ease and frequency. In addition, they made use of four distinct variations on the basic twining process, often employing more than one of them in a single article.Although a wide variety of materials was available, the Pomo people used only a few. The warp was always made of willow, and the most commonly used weft was sedge root, a woody fiber that could easily be separated into strands no thicker than a thread. For color, the Pomo people used the bark of redbud for their twined work and dyed bulrush root for black in coiled work. Though other materials were sometimes used, these four were the staples in their finest basketry.If the basketry materials used by the Pomo people were limited, the designs were amazingly varied. Every Pomo basketmaker knew how to produce from fifteen to twenty distinct patterns that could be combined in a number of different ways.The word "fashion" in line 2 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 31 to 35.The term "virus" is derived from the Latin word for poison or slime. It was originally applied to the noxious stench emanating from swamps that was thought to cause a variety of diseases in the centuries before microbes were discovered and specifically linked to illness. But it was not until almost the end of the nineteenth century that a true virus was proven to be the cause of a disease.The nature of viruses made them impossible to detect for many years even after bacteria had been discovered and studied. Not only are viruses too small to be seen with a light microscope, they also cannot be detected through their biological activity, except as it occurs in conjunction with other organisms. In fact, viruses show no traces of biological activity by themselves. Unlike bacteria, they are not living agents in the strictest sense. Viruses are very simple pieces of organic material composed only of nucleic acid, either DNA or RNA, enclosed in a coat of protein made up of simple structural units. (Some viruses also contain carbohydrates and lipids.) They are parasites, requiring human, animal, or plant cells to live. The virus replicates by attaching to a cell and injecting its nucleic acid.’ once inside the cell, the DNA or RNA that contains the virus' genetic information takes over the cell's biological machinery, and the cell begins to manufacture viral proteins rather than its own.All of the following may be components of a virus EXCEPT____________.
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 31 to 35.The term "virus" is derived from the Latin word for poison or slime. It was originally applied to the noxious stench emanating from swamps that was thought to cause a variety of diseases in the centuries before microbes were discovered and specifically linked to illness. But it was not until almost the end of the nineteenth century that a true virus was proven to be the cause of a disease.The nature of viruses made them impossible to detect for many years even after bacteria had been discovered and studied. Not only are viruses too small to be seen with a light microscope, they also cannot be detected through their biological activity, except as it occurs in conjunction with other organisms. In fact, viruses show no traces of biological activity by themselves. Unlike bacteria, they are not living agents in the strictest sense. Viruses are very simple pieces of organic material composed only of nucleic acid, either DNA or RNA, enclosed in a coat of protein made up of simple structural units. (Some viruses also contain carbohydrates and lipids.) They are parasites, requiring human, animal, or plant cells to live. The virus replicates by attaching to a cell and injecting its nucleic acid.’ once inside the cell, the DNA or RNA that contains the virus' genetic information takes over the cell's biological machinery, and the cell begins to manufacture viral proteins rather than its own.The author implies that bacteria were investigated earlier than viruses because____________.
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 31 to 35.The term "virus" is derived from the Latin word for poison or slime. It was originally applied to the noxious stench emanating from swamps that was thought to cause a variety of diseases in the centuries before microbes were discovered and specifically linked to illness. But it was not until almost the end of the nineteenth century that a true virus was proven to be the cause of a disease.The nature of viruses made them impossible to detect for many years even after bacteria had been discovered and studied. Not only are viruses too small to be seen with a light microscope, they also cannot be detected through their biological activity, except as it occurs in conjunction with other organisms. In fact, viruses show no traces of biological activity by themselves. Unlike bacteria, they are not living agents in the strictest sense. Viruses are very simple pieces of organic material composed only of nucleic acid, either DNA or RNA, enclosed in a coat of protein made up of simple structural units. (Some viruses also contain carbohydrates and lipids.) They are parasites, requiring human, animal, or plant cells to live. The virus replicates by attaching to a cell and injecting its nucleic acid.’ once inside the cell, the DNA or RNA that contains the virus' genetic information takes over the cell's biological machinery, and the cell begins to manufacture viral proteins rather than its ownThe word "nature” 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 31 to 35.The term "virus" is derived from the Latin word for poison or slime. It was originally applied to the noxious stench emanating from swamps that was thought to cause a variety of diseases in the centuries before microbes were discovered and specifically linked to illness. But it was not until almost the end of the nineteenth century that a true virus was proven to be the cause of a disease.The nature of viruses made them impossible to detect for many years even after bacteria had been discovered and studied. Not only are viruses too small to be seen with a light microscope, they also cannot be detected through their biological activity, except as it occurs in conjunction with other organisms. In fact, viruses show no traces of biological activity by themselves. Unlike bacteria, they are not living agents in the strictest sense. Viruses are very simple pieces of organic material composed only of nucleic acid, either DNA or RNA, enclosed in a coat of protein made up of simple structural units. (Some viruses also contain carbohydrates and lipids.) They are parasites, requiring human, animal, or plant cells to live. The virus replicates by attaching to a cell and injecting its nucleic acid.’ once inside the cell, the DNA or RNA that contains the virus' genetic information takes over the cell's biological machinery, and the cell begins to manufacture viral proteins rather than its own.The word "proven" in the passage is closest meaning to____________.