Climate, more than any other single factor, 11 the distribution of life on Earth. Climatic boundaries establish the limits within which organisms can survive. Plants, even more than animals, must be 12 adapted to climate in order to survive. They cannot move about or take shelter but must be equipped to 13 whatever weather conditions are likely to occur. In the harsh conditions of the far north of the earth, for example, low growing mosses, lichens, and a few flowering plants all hold to the ground for shelter from icy winds.
Animals, despite their 14 to move about and find shelter, are just as much influenced by climate as plants are. Creatures such as the camel and the penguin are so highly specialized that they have an 15 limited distribution. Others, such as bears, are flexible enough to adapt to a 16 range of climates.. Ocean-dwelling organisms are just as sensitive to climatic changes—in this case temperature and salinity—as land animals. Reef corals can survive only in clear warm seawater. Certain foraminaters are so sensitive to changes in their 17 that their presence can be taken as an 18 of sea temperature. Human beings are among the 19 specialized of all animals and can live almost anywhere. Their clothes and their homes 20 as a sort of "miniature climate" that can be taken with them everywhere.
A. ntly
E. x
I.
M. ronment
参考答案
II. B 12. L 13. I 14. C 15. J 16. E 17. O 18. H 19. A 20. C
part 2Scientists at Sussex University appear to be on the way to 11 how the mosquito, carrier of diseases such as malaria and yellow fever, homes in on its target. The problem is that they have found that the best way to avoid being bitten is: stop breathing, stop sweating, and keep down the temperature of your immediate surroundings. 12 the first suggestion is impossible and the others very difficult.
Scientists have found that there are three 13 stages in a mosquito's assault. Stage one is at fifty feet away, when the insect first smells a man or a animal to 14 . Stage two is thought to come into operation about twenty-five feet from the target, when the insect becomes guided by the carbon dioxide breathed out by the intended victim. Stage three is when the mosquito is only a matter of inches from its 15 the warmth and moisture given off by the victim is the final clue.
The researchers then * 16 how repellents interfere with its three-stage attack. They found repellents act more subtly than by just giving off a nasty smell. A Canadian researcher says that repellents appear to 17 mosquitoes first when it is following the carbon dioxide and second during the final approach, where the warmth and moisture are the insect's 18 .
Air pervaded by one of the many chemical repellents stops the mosquito reacting to the victim's carbon dioxide, and the repellent seems to affect the tiny hairs with which the insect senses moisture in the air. The sensors are blocked so that the 19 does not know whether it is flying through a moist current, or
the sensors are made to send the 20 signals.
A. examined al g ct
E. bite rtunately nting inct
I. prey e ked nite
M. Unnecessarily use overing
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11. O 12. F 13. H 14. E 15. I 16. A 17. N 18. J 19. D 20. C
