题目材料
The golden toad of Costa Rica, whose beauty and rarity inspired an unusual degree of human interest from a public generally unconcerned about amphibians, may nevertheless have been driven to extinction by human activity. In the United States, a public relations campaign raised money to protect the toad`s habitat in Costa Rica, establishing the Monteverde Cloud Forest Preserve in 1972. However, setting aside habitat was not enough to save the species. The toad's demise in the late 1980s was a harbinger of further species extinction in Costa Rica. Since that time, another twenty of the fifty species of frogs and toads known to once inhabit a 30 square kilometer area near Monteverde have disappeared.
Between one third and one half of the world`s amphibian species-including frogs, toads, and salamanders-have declined or disappeared. Scientists hypothesize that the more subtle effects of human activities on the world's ecosystems, such as the accretion of pollutants, the decrease in atmospheric ozone, and changing weather patterns due to global warming, are beginning to take their toll. Perhaps amphibians - whose permeable skin makes them unusually sensitive to environmental changes - are the biological harbingers of the natural world, giving humans early notification of the deterioration, if not destruction, of our ecosystem.
The primary purpose of the passage is to
- Adiscuss the disappearance of a particular species
- Bexplain why a certain cause is to blame for a global phenomenon
- Cargue that a class of animals should be protected from decline or extinction
- Ddescribe the global decline of a class of animals and consider possible causes
- Edemonstrate the reasons for the demise of a particular species
显示答案
正确答案: D