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[单选题]
We cannot（）for long without food and drink.
A.support
B.maintain
C.remain
D.survive
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题目内容
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题目内容
（请给出正确答案）
A.support
B.maintain
C.remain
D.survive
如果结果不匹配，请 联系老师 获取答案
更多“We cannot（）for long without fo…”相关的问题
When we see well, we do not think about our eyes very often. (79) It is only when we cannot see perfectly that we realize how important our eyes are.
People who are nearsighted can only see things that are very close to their eyes. Everything else seems blurry (模糊的). Many people who do a lot of close work, such as writing, reading and sewing, become nearsighted. Then they have to wear glasses in order to see distant objects clearly.
People who are farsighted suffer from just the opposite problem. They can see things that are far away, but they have difficulty in reading a book unless they hold it at arm's length. If they want to do much reading, they must get glasses, too.
Other people do not see clearly because their eyes are not exactly the right shape. They have what is called astigmatism (散光). This, too, can be corrected by glasses. Some people's eyes become cloudy because of cataracts (白内障). Long ago these people olden became blind. Now, however, it is possible to operate on the cataracts and remove them.
Having two good eyes is important for judging distances. Each eye sees things from a slightly different angle. To prove this to yourself, look at object out of one eye; then look at the same object out of your other eye. You will find the object's relation to the background and other things around it has changed. The difference between these two different eye views helps us to judge how far away an object is. People who have only one eye cannot judge distance as people with two eyes.
We should take good care of our eyes ______.
A．only when we can see well
B．only when we cannot see perfectly
C．even if we can see dell
D．only when we realize how important our eyes are
People who are near-sighted can only see things that are very close to their eyes.' Everything else is not so clear. Many people who do a lot of close work, such as writing, reading and sewing, become near sighted. Then they have to wear glasses in order to see distant (远处的) things clearly.
People who are far-sighted suffer from just the opposite problem. They can see things that are far away, but they have difficulty in reading a book unless they hold it at arm's length. If they want to do much reading, they must get glasses, too.
Other people do not see clearly because their eyes are not exactly the right shape. They have what is called astigmatism (散光). This, too, can be corrected by glasses. Some people's eyes become cloudy because of cataracts (白内障). Long ago these people often became blind. Now, however, it is possible to operate on the cataracts and remove them."
Having two good eyes is important for judging distances. Each eye sees things from a slightly different angle (角度). To prove this to yourself, look at an object out of one eye; then look at the same object out of the other eye. You will find the object's relation to the background (背景) and other things around it has changed. The difference between these two different eye views helps us to judge how far away an object is. People who have only one eye cannot judge distance as people with two eyes.
We should take good care of our eyes ______.
A．only when we cannot see perfectly
B．only when we can see well
C．even if we can see well
D．only when we realize how important our eyes are
Crocodiles(鳄鱼)lay their eggs and leave them under leaves or sand. Baby crocodiles have special sharp teeth with which to break their way out of the shells. Crocodiles only live where it is hot. They are found in India, Australia, Africa and America. They spend most of their time lying around in the mud or the rivers. The crocodiles long powerful tail is used when the animal is swimming. It is also an excellent weapon, because it can be swung with great speed and force. One blow will knock down a man or even a big animal at once. The crocodile is very well protected against its enemies by the hard bony plates which cover most of its body, but because of the way its neck is formed, it cannot turn its head from side to side and so it can only see in front of itself. The crocodile has its teeth cleaned by the crocodile bird. For its food this bird takes the bits left in the crocodiles mouth. This helps the crocodile, which cannot clean its own teeth, for it cannot move its tongue up and down. With its rows of terrible pointed teeth it seizes its food, which may be a fish, an animal, or even a careless human being, and then holds it below the water until it is drown to death. The long-nosed crocodile is shy and timid and because of this, the people of West Africa where it lives, sometimes catch it for food. Many, many centuries ago there were crocodiles in England. We know this because we have found their bones buried far down in the earth on which London is built. But the Britain of today is too cold for them to live in. Crocodiles may grow to over thirty feet in length. When they lie floating in the water, they look like floating tree-trunks and it is often impossible to tell that they are there.
The female crocodile______.
A．buries her eggs
B．sits on her eggs
C．carries her eggs
D．eats her eggs
【B1】
A．although
B．rather
C．though
D．therefore
Bacteria (细菌) are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in microns. One micron is a thousandth of a millimeter: a pinhead is about a millimeter across. Rod-shaped bacteria are usually from two to four microns long, while rounded ones are generally one micron in diameter. Thus, if you enlarged a rounded bacterium a thousand times, it would be just about the size of a pinhead. An adult human magnified by the same amount would be over a mile (1.6 kilometers) tall.
Even with an ordinary microscope, you must look closely to see bacteria. Using a magnification of 100 times, one finds that bacteria are barely visible as tiny rods or dots. One cannot make out anything of their structure. Using special stains, one can see that some bacteria have attached to them wavy-looking "hairs" called flagella. Others have only one flagellum. The flagella rotate, pushing the bacteria through the water. Many bacteria lack flagella and cannot move about by their own power, while others can glide along over surfaces by some little-understood mechanism.
From the bacterial point of view the world is a very different place from what it is to humans.To a bacterium water is as thick as molasses (糖蜜) is to us. Bacteria are so small that they are influenced by the movements of the chemical molecules around them. Bacteria under the microscope even those with no flagella often bounce about in the water. This is because they collide with the water molecules and are pushed this way and that molecules move so rapidly that within a tenth of a second the molecules around a flagellum have been replaced by new ones. Even bacteria without flagella are thus constantly exposed to a changing environment.
Which of the following is the main topic of the passage？
A．The characteristics of bacteria.
B．How bacteria reproduce.
C．The various functions of bacteria.
D．How bacteria contribute to disease.
So why is this huge increase in population taking place？ It is really due to the spread of the knowledge and practice of what is becoming known as "Death Control". You have no doubt heard of the term "Birth Control". "Death Control" is something rather different. It recognizes the work of the doctors and scientists who now keep alive people who, not very long ago, would have died of a variety of then incurable diseases. Through a wide variety of technological innovations that include farming methods and the control of deadly diseases, we have found ways to reduce the rate at which we die. However, this success is the very cause of the greatest threat to mankind.
If we examine the amount of land available for this ever-increasing population, we begin to see the problem. If everyone on the planet had an equal share of land, we would each have about 50,000 square meters. This figure seems to be quite encouraging until we examine the amount of usable land we actually have. More than three-fifths of the world's land cannot produce food.
Obviously, with so little land to support us, we should be taking great care not to reduce it further. But we are not! Instead, we are consuming its "capital" — its nonrenewable fossil fuels and other mineral deposits that took millions of years to form. but which are now being destroyed in decades. We are also doing the same with other vital resources not usually thought of as being nonrenewable such as fertile soils, groundwater and the millions of other species that share the earth with us.
It is a very common belief that the problems of the population explosion are caused mainly by poor people living in poor countries who do not know enough to limit their reproduction. This is not true. The actual number of people in an area is not as important as the effect they have on nature. Developing countries do have an effect on their environment, but it is the populations of richer countries that have a far greater impact on the earth as a whole.
According to the article, what contributes to the population increase？
A．Birth explosion.
B．Birth Control.
C．Technological innovations.
D．Death Control.
Unfortunately, many salespeople are【C8】______to tell the truth. They【C9】______some in formation, or share partial truths, or just plain lie. They do it in the【C10】______that customers will buy when they hear【C11】______they want to hear. It is true that customers want to hear certain things but【C12】______they are true. Let's go back to the restaurant.【C13】______the wait is not 15minutes-it is 90 minutes. It is not what we want to hear. Still, we can decide to stay or not to stay. If we do not stay, we will be hack. But if we【C14】______told 30 minutes and it became 90, that【C15】______the last time we ate there. Sooner or later, customers al ways find out the truth. If the truth is different than what they have been told, you have lost their trust.
Truth is【C16】______accuracy. It includes a willingness to stand behind what you say. In other words, are you willing to put your money【C17】______your mouth is？ If you are working with others, part of their【C18】______is that when something goes wrong you will stand with them. If an order is delayed, for example, how will you help them【C19】______their business commitments？ Part of earning their trust is having a backup plan in place should your【C20】______systems fail.
【C1】
A．takes
B．spends
C．lasts
D．relies
This is a nice car, but we cannot ______ it.
A．provide
B．afford
C．supply
D．manage
The sentence "He cannot help it" (Para. 3, Line l) most probably means " ______".
A．man cannot avoid destroying the environment
B．man cannot obtain resources he needs from other planets
C．man cannot survive for a long time
D．man cannot help to create a new environment
Under this ______, we cannot choose but obey him.
A．circumstance
B．surrounding
C．situation
D．environment
