Passage Three
17.
A) Whether it can be detected and checked.
B) Whether it will lead to widespread food shortage.
C) Whether global warming will speed up in the future.
D) Whether it will affect their own lives.

18.
A) Many species have moved further north.
B) Many new species have come into existence.
C) Many species have developed a habit of migration.
D) Many species have become less sensitive to climate.

19.
A) Storms and floods.
B) Disease and fire.
C) Less space for their growth.
D) Rapid increase of the animal population.

20.
A) They will gradually die out.
B) They will be able to survive in the preserves.
C) They will have to migrate to find new homes.
D) They will face extinction without artificial reproduction.

答案及参考原文：

DABC

If the earth gets hotter in the new century, what will happen to animals and the plants which animals depend on for survival? The question offers another way of looking at the greenhouse effect. People have talked about the general problem of global warming for some time. But they were usually worried about things like whether to buy a home on the coast(17). Biologists and others scientists turned their attention to plants and animals at an important meeting that took place last October. They reviewed evidence that plants and animals are sensitive to climate. Since the Ice age ended 2,000 years ago, and warmer temperatures returned to the northern latitudes, many species have migrated north(18). If the predictions about the greenhouse are correct, temperatures will rise by the same amount in the next 100 years as they did in the past 10,000. Will animals and plants be able to adapt that quickly to change in the environment? Many won't. Certain species will probably become very rare. Experts say plants under climate stress will very open to disease and fire(19). Forest fires may become more common. That in turn may harm animals that depend on the trees for food or shelter. Any preserves we set up to protect the endangered species may become useless as the species are forced to migrate along with their natural homes(20). Changes are part of life, but rapid change says scientist George Woodwill, is the enemy of life.

17. What is the concern of ordinary people about the greenhouse effect?
18. What has happened since the end of Ice age?
19. What will be a possible threat to plants in the future?
20. According to the passage, what will probably happen to the endangered species?