医学考博公共英语模拟试题三

　　Part IV. Reading Comprehension (30%)

　　Directions: In this part of the test there are six passages. Following each passage there are five questions with four choices. Choose the best answer and mark your answer on the ANSWER SHEET.

　　Passage One

　　Cells cannot remain alive outside certain limits of temperature, and much narrower limits mark the boundaries of effective functioning. Enzyme (酶) systems of mammals and birds are most efficient only within a narrow range around 37ºC; a departure of a few degrees from this value seriously impairs their functioning. Even though cells can survive wider fluctuations, the integrated actions of bodily systems are impaired. Other animals have a wider tolerance for changes of bodily temperature.

　　For centuries it has been recognized that mammals and birds differ from other animals in the way they regulate body temperatures. Ways of characterizing the difference have become more accurate and meaningful over time, but popular terminology still reflects the old division into “warm-blooded’ and “cold-blooded” species; warm-blooded included mammals and birds, whereas all other creatures were considered cold-blooded. As more species were studied, it became evident that this classification was inadequate. A fence lizard or a desert iguana (鬣蜥)—each cold-blooded—usually has a body temperature only a degree or two below that of humans and so is not cold. Therefore the next distinction was made between animals that maintain a constant body temperature, called homotherms(同温动物), and those whose body temperature varies with their environment, called poikilotherms(变温动物). But this classification also proved inadequate, because among mammals there are many that vary their body temperatures during hibernation. Furthermore, many invertebrates(无脊椎动物) that live in the depths of the ocean never experience a change in the chill of the deep water, and their body temperatures remain constant.

　　The current distinction is between animals whose body temperature is regulated chiefly by internal metabolic processes and those whose temperature is regulated by, and who get most of their heat from, the environment. The former are called endotherms (恒温动物), and the latter are called ectotherms (外温动物). Most ectotherms do regulate their body temperature, and they do so mainly by locomoting to favorable sites or by changing their exposure to external sources of heat. Endotherms (mainly mammals and birds) also regulate their temperature by choosing favorable environments, but primarily they regulate their temperatures by making a variety of internal adjustments.

　　61. The passage mainly discusses _______.

　　A. body temperatures of various animals

　　B. the newest research on measuring temperature

　　C. methods of temperature reduction

　　D. the classification of animals by temperature regulation

　　62. Which of the following terms refers primarily to mammals and birds?

　　A. Warm-blooded. B. Ectothermic.

　　C. Cold-blooded. D. Poikilothermic

　　63. In general, the temperature of endotherms is regulated _______.

　　A. consciously B. internally

　　C. inadequately D. environmentally

　　64. According to the passage, the chief way in which ectotherms regulate their temperature is by

　　_______.

　　A. seeking out appropriate locations

　　B. hibernating part of the year

　　C. staying in deep water

　　D. triggering certain metabolic processes

　　65. According to the passage, human beings mainly regulate their body temperatures by _______.

　　A. choosing favorable environments B. internal metabolic processes

　　C. eating more food D. doing physical exercises

　　Passage Two

　　The narrow passage ended in a round arch fringed with ivy and creepers. The children passed through the arch into a narrow ravine whose banks were of stone, moss-covered. Trees growing on the top of the bank arched across and the sunlight came through in changing patches of brightness. The path, which was of greeny-grey stones where heaps of leaves had drifted, sloped steeply down, and at the end of it was another round arch, quite dark inside, above which were rose rocks and grass and bushes.

　　“It’s like the outside of a railway tunnel,” said Jimmy.

　　“It might be the entrance to an enchanted castle,” said Kathleen.

　　Under the drifted damp leaves the path was firm and stony. At the dark arch they stopped.

　　“There are steps down,” said Gerald.

　　Very slowly and carefully they went down the steps. Gerald struck a match when the last step was found to have no edge and to be in fact the beginning of a passage turning to the left.

　　“This,” said Jimmy, “might take us back to the road.”

　　“Or under it,” said Gerald, “we’ve come down eleven steps.”

　　They went on, following Gerald, who went very slowly for fear, as he explained, of steps. The passage was very dark.

　　Then came a glimmer of daylight that grew and grew and presently ended in another arch that looked out over a scene so like a picture out of a book about Italy that everyone’s breath was taken away, and they simply walked forward silent and staring. A short avenue of cypresses led, winding as it went, to a marble terrace that lay broad and white in the sunlight. The children, blinking, leaned their arms on the flat balustrade (栏杆) and gazed.