二、阅读理解

　　The "balance of nature" is not an empty phrase. Nature provides a population to occupy a suitable environment and cuts down surplus population to fit the available food supply. One means of reducing surplus population is predators(食肉动物); others are parasites(寄生虫)and diseases. Also, population density produces nervous disorders and even drives animals to mass migrations, like the lemmings(旅鼠)of Norway who plunge into(跳入)the sea.

　　That predators populations increase to control other animals has long been known. Many years ago, the Hudson's Bay Company records revealed that the fox population went up and down about a year after the rabbit population had gone up and down.

　　Sometimes a situation occurs in which the predators population is reduced to a level below that which nature can readily replace. On Valcour Island in Lake Champlain(New York), a costly campaign resulted in the elimination of predatory animals only to have birds and small animals—including grouse(松鸡)and hares, popular game(猎物)—increase for four years afterward. Then lacking predator control, nature resorted to cut down these populations.

　　Jamaica had an example of nature's persistence in providing animals for existing habits. Sugar planters, about 75 years ago, imported mongooses to control rats. The mongooses killed off the rats and, with plentiful food, multiplied. Rats became scarce and the mongooses ate lambs, kids, puppies(小狗), and wildlife. Eventually, food became scarce and the mongoose's population declined.

　　11. According to the article, the phrase "balance of nature" means ______.

　　A. the relation of wildlife to man

　　B. the adequacy of the food supply to support its animal population

　　C. the ratio of small game to predators

　　D. the destruction of predators

　　答案：B

　　12. The effect of predator control over other animal populations ______.

　　A. has just been learned B. is not recent knowledge

　　C. is not important now D. was learned in Norway

　　答案：B

　　13. When predators control is not available, nature brings animal population into balance by resorting to ______.

　　A. hunters B. diseases

　　C. storms and flood D. forest fires

　　答案：B

　　14. When the mongooses in Jamaica killed off the rats, they ______.

　　A. quickly died for lack of food B. attacked humans

　　C. became problems themselves D. ate the sugar crop

　　答案：C

　　15. Implied but not stated: ______.

　　A. Sugar planters imported mongooses to control rats

　　B. Man should never tamper(损害)with nature

　　C. To upset the balance of nature can be troublesome

　　D. Man has complete control over nature

　　答案：C　The Chinese of 3500 years ago believed that the earth was a chariot, and the sky was a curved canopy(天空)stretched above it. The canopy was nine layers thick, and it sloped slightly to the northwest, as a cataclysm(地陷)had broken one of its supporting columns. This gentle slope explained the movement of the stars from east to west.

　　According to these ancient Chinese beliefs, the sun spent the night on earth and ascended to the sky each morning from the luminous valley of the earth by climbing the branches of an immensely tall sacred tree. To the Chinese people, the sun was the incarnation of goodness, beauty, and truth. In popular imagination, the sun was represented as a cock that little by little assumed human form. His battles with the dragons, which personified evil in their beliefs, accounted for momentary disappearances of the sun that men now call eclipses. Many of the Chinese people worshiped the sun, but in the vast and complicated organization of the Chinese gods, the sun was of only secondary importance.

　　Along with these unsophisticated beliefs about the sun, the Chinese evolved a science of astronomy based upon observation—though essentially religious—which enabled them to predict eclipses of the sun and the movement of the stars. Such predictions were based on calculations made by using a gnomon(【天文】日晷仪指针)—an object whose shadow could be used as a measure, as with a sundial or simple shadow pointers. Moreover, with the naked eye, the Chinese observed sunspots, a phenomenon not then known to their contemporaries.

　　16. The ancient Chinese believed that the earth ______.

　　A. was a chariot B. sloped to the northwest

　　C. was supported by columns D. had nine layers

　　答案：A

　　17. To the Chinese people, the sun represented ______.

　　A. the primary god B. evil

　　C. goodness, beauty and truth D. combat

　　答案：C

　　18. The sun‘s disappearances were thought to be caused by ______.

　　A. fights with cocks B. fights with dragons

　　C. a scientific phenomenon D. eclipse

　　答案：B

　　19. Ancient Chinese astronomy could be accurately described as ______.

　　A. entirely religious in nature B. based on legendary figures

　　C. advanced in some areas D. completely unsuccessful

　　答案：A

　　20. Implied but not stated: ______.

　　A. The sun was worshiped by all the Chinese people

　　B. The sun was thought of as a cock

　　C. Chinese religion and astronomy were closely interrelated

　　D. Sundials were first used by the Chinese

　　答案：D