2017年6月大学英语六级模拟试题（13）

>>英语六级题库：2017年6月大学英语六级模拟试题

Section C (Compound Dictation)略

Part II Reading Comprehension (35 minutes)

Directions: There are 4 reading passages in this part. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A., B., C. and D. You should decide on the best choice and mark the corresponding letter on the Answer Sheet with a single line through the center.

Questions 21 to 25 are based on the following passage:

For all their great diversity of shapes and sizes, glaciers can be divided into two essential types: valley glaciers, which flow downhill from mountains and are shaped by the constraints of topography(地貌), and ice sheets, which flow outward in all directions from dome—like centers of accumulated ice to cover vast expanse of terrain. Whatever their type, most glaciers are remnants of great shrouds of ice that covered the earth eons ago. In a few of these glaciers the oldest ice is very ancient indeed; the age of parts of the Antarctic sheet may exceed 500,000 years.

Glaciers are born in rocky womb above the snow line, where there is sufficient winter snowfall and summer cold for snow to survive the annual melting. The long gestation period of a glacier begins with the accumulation and gradual transformation of snow flakes. Soon after they reach the ground, complex snowflakes are reduced to compact, roughly spherical ice crystals, and the basic components of a glacier. As new layers of snow and firn, snow that survives the melting of the previous summer, accumulate, they squeeze out most of the air bubbles trapped within and between the crystals below. This process of recrystallization continues throughout the life of the glacier.

The length of time required for the creation of glacier ice depends mainly upon the temperature and the rate of snowfall. In Iceland, where snowfall is heavy and summer temperatures are high enough to produce plenty of melt—water, glacier ice may come into being in a relatively short time—say, ten years. In parts of Antarctica, where snowfall is scant and the ice remains well below its melting temperature year round, the process may require hundreds of years.

The ice does not become a glacier until it moves under its own weight, and it cannot move significantly until it reaches a critical thickness—the point at which the weight of the piled—up layers overcomes the internal strength of the ice and the friction between the ice and the ground. This critical thickness is about 60 feet. The fastest moving glaciers have been gauged at not much more than two and a half miles per year, and some cover less than 1/100 inch in that same amount of time. But no matter how infinitesimal the flow, movement is what distinguishes a glacier from a mere mass of ice.

21. Which of the following is the most appropriate definition of glacier?

A. Glaciers fall into two basic categories: valley glaciers and ice sheets.

B. Glaciers are huge masses of ice that move under their own weight.

C. Glaciers either flow downhill from mountains or flow outward in all directions from dome—like centers of accumulated ice.

D. Glaciers are primarily formed in the rocky mountain tops above the snow line.

22. What is implied in the passage?

A. Glaciers can be divided into many categories according to their shapes and sizes.

B. Ice sheets move faster than valley glaciers.

C. It takes longer for glaciers to form in Antarctica than in Iceland.

D. Valley glaciers are not as old as ice sheets.

23. Why does the author mention the formation of glaciers in Iceland in the third paragraph?

A. Heavy snowfall and high summer temperatures make glaciers come into existence in a relatively short period of time in Iceland.

B. Iceland contains some of the oldest ice sheets in existence.

C. Iceland has one of the best—preserved glaciers in the world.

D. People expect to find some relatively new glaciers in Iceland.

24. What analogy did the author use when describing the formation of glaciers?

A. womb B. trap C. crystal D. birth

25. Which of the following is the best title for the article?

A. Formation of Glaciers B. Sizes and Shapes of Glaciers

C. The History of Glaciers D. Why Do Glaciers Move?

Questions 26 to 30 are based on the following passage:

Botany, the study of plants, occupies a peculiar position in the history of human knowledge. For many thousands of years it was the one field of awareness about which humans had anything more than the vaguest of insights. It is impossible to know today just what our Stone Age ancestors knew about plants, but from what we can observe of pre—industrial societies that still exist, a detailed learning of plants and their properties must be extremely ancient. This is logical. Plants are the basis of the food pyramid for all living things, even for other plants. They have always been enormously important to the welfare of people, not only for food, but also for clothing, weapons, tools, dyes, medicines, shelter, and a great many other purposes. Tribes living today in the jungle of the Amazon recognize literally hundreds of plants and know many properties of each. To them botany, as such, has no name and is probably not even recognized as special branch of “knowledge" at all.

Unfortunately, the more industrialized we become the farther away we move from direct contact with plants, and the less distinct our knowledge of botany grows. Yet everyone comes unconsciously on an amazing amount of botanical knowledge, and few people will fail to recognize a rose, an apple, or an orchid. When our Neolithic ancestors, living in the Middle East about 10,000 years ago, discovered that certain grasses could be harvested and their seeds planted for richer yields the next season, the first great step in a new association of plants and humans was taken. Grains were discovered and from them flowed the marvel of agriculture: cultivated crops. From then on, humans would increasingly take their living from the controlled production of a few plants, rather than getting a little here and a little there from many varieties that grew wild. And the accumulated knowledge of tens of thousands of years of experience and intimacy with plants in the wild would begin to fade away.

26. According to the first paragraph, early humans .

A. did not enjoy the study of botany

B. placed great importance on the ownership of properties

C. probably had extensive knowledge about plants

D. didn't know how to cultivate crops

27. The word “this” in the sentence “This is logical” most probably refers to.

A. that our ancestors knew plants are the basis of the food pyramid for all living things

B. that our ancestors' knowledge about plants and their properties was very detailed and organized

C. that extensive knowledge about plants and their properties are essential in the cultivation of crops in pre—industrial societies

D. that a detailed learning of plants and their properties was not obtained until the pre—industrial societies came into being

28. According to the author, when did our knowledge of botany become less distinct?

A. As our society become industrialized.

B. As our direct contact with plants increases.

C. As urbanization took place.

D. As we became less interested in the extensive botanical knowledge.

29. Why does the author mention tribes living in the jungle of the Amazon in the passage?

A. To show that people who have no contact with modern civilization have no idea what the term botany means.

B. To show even the most primitive people have extensive knowledge about plants and their properties.

C. To show how important the study of botany is to human beings.

D. To show that how people unconsciously come into possession of an amazing amount of botanical knowledge.

30. The relationship between botany and agriculture is similar to the relationship between the study of animals and .

A. sheep raising B. bird watching

C. deer hunting D. horse riding

Questions 31 to 35 are based on the following passage:

The great advance in rocket theory 40 years ago showed that liquid—fuel rocket were far superior in every respect to the skyrocket with its weak solid fuel, the only kind of rocket then known. However, during the last decade, large solid—fuel rockets with solid fuels about as powerful as liquid—fuels have made their appearance, and it is a favorite layperson's question to inquire which one is better. The question is meaningless; one might as well ask whether a gasoline or a diesel engine is better. It all depends on the purpose. A liquid—fuel rocket is complicated, but has the advantage that it can be controlled beautifully. The burning of the rocket engine can be stopped completely; it can be re—ignited when desired. In addition, the thrust can be made to vary by adjusting the speed of the fuel pumps. A solid—fuel rocket, on the other hand, is rather simple in construction, though hard to build when a really large size is desired. But once you have a solid—fuel rocket, it is ready for action at very short notice. A liquid—fuel rocket has to be fueled first and cannot be held in readiness for very long after it has been fueled. However, once a solid—fuel rocket has been ignited, it will keep burning. It cannot be stopped and re—ignited whenever desired (it could conceivably be stopped and re—ignited after a pre—calculated time of burning has elapsed) and its thrust cannot be varied. Because a solid—fuel rocket can be kept ready for a long time, most military missiles employ solid fuels, but human—piloted space flight needs the fine adjustments that can only be provided by liquid fuels. It may be added that a liquid—fuel rocket is an expensive device; a large solid—fuel rocket is, by comparison, cheap. But the solid fuel, pound per pound, costs about 10 times as much as the liquid fuel. So you have, on the one hand, an expensive rocket with a cheap fuel and on the other hand a comparatively cheap rocket with an expensive fuel.

31. Which of the following is implied in the passage?

A. Rockets using liquid fuel was not available 40 years ago although researches were being done on the practicability of using liquid fuel in rockets.

B. It was not until the last decade that rockets using solid fuels made their appearance.

C. Complicated rockets using solid fuel have the advantage of flexibility and adjustability that liquid—fuel rockets don't possess.

D. Liquid fuel costs about 10 times as much as the solid fuel costs.

32. Which of the following was NOT mentioned as one of the advantages of liquid?fuel rockets?

A. They are easy to control. B. Their thrust is variable.

C. They are easy to construct. D. Their speed is adjustable.

33. Solid—fuel rockets are expensive to operate because of their .

A. burning time B. size C. fuel D. engines

34. The chief consideration for using liquid fuels in human—piloted space flights is that the rocket .

A. is inexpensive to construct B. is capable of carrying heavy cargo

C. is easy to control D. is inexpensive to operate

35. Which of the following statements is true about solid—fuel rockets?

A. They are simple to construct.

B. They can be re—ignited when desired.

C. They can provide fine adjustments in operation.

D. They cost a lot less than liquid—fuel rockets to construct.

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