Dinosaurs, saber-tooth tigers and the dodo bird are famous examples __1__ of animals that have become extinct. In case of the dinosaurs, it __2__ seems likely that a catastrophic event alters the global climate __3__ enough to lead to their disappearance. More recent extinctions and near-extinctions-such as the blue whales, tiger, panda, and __4__ North American bison―have been the direct result of human activity. By the early 1990s, species were becoming extinct at a rate of three per hour, or 27,000 every day ? a figure quoted by the American biologist Edward O.Wilson of Harvard University, based on his most conservative estimates. This rate of extinctions carries with it some terrible consequences. Each plant that becomes extinct,for example, may take with it as much as 30 insects and animals __5__ that depend on it for food. Habitat loss is one of the most important causes of extinction. For rising populations in many countries __6__ lead to the clearing of more land, habitats such as raining forest __7__ and grasslands disappear.

　　In the East Africa, once renowned for its wildlife, few wild animals __8__ remain living outside the boundaries of national parks and game __9__ reserves. In other parts of the world, coastal ecosystems are clearing __10__ for development. Wetland areas are drying out as a result of water extraction to support farming and tourism. Bird species are among the worst affected by the loss of wetlands.

　　答案：

　　1.saber-tooth―saber-toothed。如果是“形容词+名词”作前置修饰语，那么名词要加-ed。

　　2.^case―the。in case of 和 in the case of 的意思是不同的，前者的意思是“万一”，后者的意思是“在……的情况中”

　　3.alters―altered。这里谈的是恐龙灭绝的时期，所以时间是过去。

　　4.whales―whale。定冠词+可数名词的复数 是特指，所以the blue whales是特指，但是上下文并没有提及特定的蓝鲸，所以从整个句子的意思来看，这里是指物种，是类指，所以应该用“定冠词+可数名词单数”形式。

　　5.much―many。insects and animals 是可数名词，所以应该说as many as

　　6.For-- As/Since。尽管for作为连词可以引导原因状语分句，但是它一般不放在句首。

　　7.raining―rain。rain forest,指热带雨林

　　8.the去掉。East Africa是专有名词。

　　9.living―alive。remain是系动词，后面的形容词是主语补足语，living不能作主语补足语。

　　10.clearing―cleared。这里需要用被动语态