r failure to adapt to such conditions as competition and predation. Since the 1600s, however, the process of extinction has greatly accelerated as a result of both human population growth and technological encroachment on natural ecology systems. Today the majority of the world’s environments are changing faster than the ability of most species to adapt to such changes through natural selection.Species become extinct or endangered for number of reasons, but the primary cause is the destruction of natural habitats. Drainage of wetlands, cutting and clearing of forests, growth of cities, and highway and dam construction have seriously reduced available natural habitats. As the various surroundings become fragments, the remaining animal population crowd into smaller areas, causing further destruction of natural surroundings. Species in these small “islands” lose contact with other populations of their extinction.Some private and government efforts have been organized to save declining species. Laws were made in some countries in the early 1900s to protect wild animals from commercial trade and killing. International endeavors are shown in the convention on International Trade in Endangered Species, approved by 51 nations. Its purpose is to restrict exploitation of wild animals and plants by regulating and restricting trade in certain species. How effective such laws will be in various countries, however, depends on enforcement and support by the people and the courts. Because of lack of law enforcement, the willingness of some segments of society to trade in endangered species, the activities of people who catch and kill animals illegally and dealers who supply the trade, the future of many species is in doubt in spite of legal protection.
参考答案： A 答案解析：
1How does the author feel about the prospect of protecting endangered species from being extinct?
A.Worried B.Optimistic C.Indifferent D.Confident
参考答案： C 答案解析：
2According to the passage, which of the following is most important in saving declining species?
A.governments should make some laws to protect endangered species. B.People should pay more attention to the protection of natural surroundings. C.Relevant law must be made and enforced with the support of the people. D.Some organizations should warn people not to trade in endangered animals.
参考答案： B 答案解析：
3This passage mentions all of the following causes for the extinction of many species EXCEPT
A.natural selection of species. B.various natural disasters. C.commercial trade and killing D.destruction of natural surroundings.
参考答案： C 答案解析：
4In the last sentence of the second paragraph, the word “islands” refers to
A.the lands that are completely surrounded by water. B.the wild animals’ breeding grounds protected by law. C.the pieces of land separated by modern buildings and roads. D.the small and isolated areas inhabited by certain species.
参考答案： C 答案解析：
5According to the passage, which of the following is the most important factor causing the rapid extinction of many species since the 17th century?
A.Human beings are not aware of the importance of preserving endangered species. B.Some endangered species have already reached the end of their life span
