恩波2008年12月大学英语四级全真模拟题（五）

　　[4] 阅读理解
　　Part Ⅳ Reading Comprehension(Reading in Depth) (25 minutes)
　　Section A
　　Directions: In this section, there is a passage with ten blanks. You are required to select one word for each blank from a list of choices given in a word bank following the passage. Read the passage through carefully before making your choices. Each choice in the bank is identified by a letter. Please mark the corresponding letter for each item on Answer Sheet 2 with a single line through the centre. You may not use any of the words in the bank more than once.
　　Questions 47 to 56 are based on the following passage.
　　The comparatively treeless plains of North Africa have suffered a progressive drying up, both 47 and man-made, but the region was 48 so rich in fertile soil that the district we now know as the Libyan Desert was, in the old days, part of the granary (粮仓) of the Roman Empire, and the centre of the Sahara 49 a busy trading population for a long period. That was when there were 50 in plenty and the fields were the traditional "fields of the woods" -clearings in the forest-and therefore always tree 51 .
　　It is the trees that lift the water and send 52 into the air so that it may fall as dew or rain further on. Trees reduce the speed of the wind, and provide shelter and shade; the roots 53 minerals in the soil and these are carried to the leaves which, when they have fulfilled their function, return to the earth, giving the soil the combination of minerals that plants require.
　　But through the ages Africa has been 54 . Successive invaders have felled the forest to provide grazing lands for their flocks and herds. With the removal of the essential tree cover, the water 55 was broken, the earth became feverish and sick, and in course of time was unable to support those who had broken the 56 of life by removing the earth's green mantle-the trees.
　　
　　A) moisture B) cycle C) water D) rhythm
　　E) contain F) trap G) once H) surrounded
　　I) fed J) exploited K) social L) natural
　　M) forest N) usually O) trees
　　Section B
　　Directions:There are 2 passages in this section. 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 2 with a single line through the centre.
　　Passage One
　　Questions 57 to 61 are based on the following passage.
　　No one knows when the first calendar was developed. But it seems possible that it was based on lunar months. When people started farming, the sages of the tribes became very important, they studied the sky and gathered enough information to be able to predict when the seasons would change, and were able to announce when it was time to plant crops.
　　The divisions of time we use today were developed in ancient Babylonia 4,000 years ago.Babylonian astronomers believed the sun moved around the Earth every 365 days.They divided the trip into 12 equal parts, each with 30 days. Then they divided each day into 24 equal parts, or hours, and divided each hour into 60 minutes, each minute into 60 seconds.
　　Humans have used many devices to measure time; the sundial (日晷) was one of the earliest and simplest. However, the sundial worked well only when the weather was fine, so other ways of measuring the passing of time were invented. One device was the hourglass(沙漏). By the eighteenth century, people had developed mechanical clocks and watches. So we have devices to mark the passing of time, but what time is it now? Clocks in different parts of the world do not show the same time at the same time, because time on Earth is set by the sun's positions in the sky above us. As international communications and travel grew, it became clear that a way to establish a common time for all parts of the world was needed. In 1884, an international conference divided the world into 24 time zones, each zone represents one hour. The astronomical observatory in Greenwich, England, was chosen as the starting point for the time zones. Twelve zones are west of Greenwich. Twelve are east. The time at Greenwich measured by the sun is considered by astronomers to be Universal Time, also known as Greenwich Mean Time.
　　57. Which of the following is the best title for this passage?
　　A) The Development of Universal Time.
　　B) Different Ways to Measure Time.
　　C) Why We Measure Time the Way We do.
　　D) How the Calendar Came into being.
　　58. What does the example of Babylonia astronomers reveal?
　　A) It reveals Babylonians'wisdom that was absent elsewhere.
　　B) It reveals the origin of our time measurements.
　　C) It reveals the limits of some time measurements.
　　D) It reveals the stability of time measurements.
　　59. The author mentions all of the following ways to measure time EXCEPT .
　　A) sundial B) hourglass C) electric clock D) mechanical clock
　　60. According to the passage, Greenwich Mean Time .
　　A) provides a common time for all parts of the world
　　B) is calculated from the sun
　　C) is the 12th of the 24 time zones
　　D) was named after an international conference
　　61. With which of the following statements would the author be most likely to agree?
　　A) Time measurements have changed in response to need and technological development.
　　B) In ancient Babylonia, 12 was the basic division of time.
　　C) The first calendar was developed because the sages of tribes were intelligent.
　　D) Universal Time is so named because it is applicable throughout the universe.
　　Passage Two
　　Questions 62 to 66 are based on the following passage.
　　For many years, scientists couldn't figure out how atoms and molecules on the Earth combined to make living things. Plants, fish, dinosaurs, and people are made of atoms and molecules, but they are put together in a more complicated way than the molecules in the primitive ocean. What's more, living things have energy and can reproduce, while the chemicals on the Earth 4 billion years ago were lifeless.
　　After years of study, scientists figured out that living things, including human bodies, are basically made of amino acids and nucleotide bases. These are molecules with millions of hydrogen, carbon, nitrogen, and oxygen atoms. How could such complicated molecules have been formed in the primitive soup? Scientists were stumped.
　　Then, in 1953, two scientists named Harold Urey and Stanley L. Miller did a very simple experiment to find out what had happened on the Primitive Earth. They set up some tubes and bottles in a closed loop, and put in some of the same gases that were present in the atmosphere 4 billion years ago: water vapor, ammonia, carbon dioxide, methane, and hydrogen.
　　Then they shot an electric spark through the gases to simulate bolts of lightning on the ancient Earth, circulated the gases through some water, sent them back for more sparks, and so on. After seven days, the water that the gases had been bubbling through had turned brown. Some new chemicals were dissolved in it. When Miller and Urey analyzed the liquid, they found that it contained amino acids-the very kind of molecules found in all living things.
　　62. When did scientists come to realize how the atoms and molecules on the Earth combined to make living thing?
　　A) 4 billion years ago. B) In 1953.
　　C) After seven days. D) Many years later.
　　63. Scientists figured out that human bodies are basically made of .
　　A) amino acids
　　B) molecules
　　C) hydrogen, carbon, nitrogen and oxygen atoms
　　D) water vapor, ammonia, carbon dioxide, methane and hydrogen
　　64. Harold Urey and Stanley L.Miller did their experiment in order to .
　　A) find out what had happened on the Earth 4 billion years ago
　　B) simulate bolts of lightning on the ancient Earth
　　C) dissolve some new chemicals
　　D) analyze a liquid
　　65. At the end of the last paragraph, the word "it" refers to .
　　A) a closed loop B) an electric spark C) water D) the liquid
　　66. According to the writer, living things on the Earth include .
　　A) atoms and molecules B) chemicals
　　C) plants, fish, dinosaurs and human beings D) the primitive soup