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  3. Over the history of the earth, millions of animal and plant species have disappeared. Most of these species disappeared, or beca

Over the history of the earth, millions of animal and plant species have disappeared. Most of these species disappeared, or beca

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问题     Over the history of the earth, millions of animal and plant species have disappeared. Most of these species disappeared, or became【S1】______, because of【S2】______causes such as climatic changes or a catastrophic event, like an asteroid hitting earth.      What is different today is that most species that are in danger of becoming extinct are not endangered because of natural causes but because of【S3】______activity. Today, we will be looking at the reasons that many plants and animals are endangered and how these reasons, or causes, are related to human activity.
    They single most important cause of endangered species today is the【S4】______and degradation of habitat (栖息地). Most animals and plants are【S5】______live and reproduce in a specific environment, habitat. They cannot【S6】______if they lose the specific habitat that they are adapted to live and reproduce in.
    There are many ways that human activity destroys habitat. For example, forests, grasslands, and deserts, which provide habitat to many plants and animals, are【S7】______in order to develop residential areas for people to live in and industrial area for people to work in. Land is also cleared to prepared it for farmers to grow crops on. Swamps and marshes, which provide habitat to many animal and plant species, are often【S8】______and filled in, also to provide land for development or agriculture.【S9】______rivers are sometimes dammed (筑坝) in order to provide people with electrical power. All of these human activities, such as clearing forests, grasslands, and deserts; draining (排水)swamps and marshes, and damming rivers【S10】______the destruction of habitats that many plants and animals need to live and reproduce in.

A) extinct            B) natural           C) survive            D) anniversary
E) destruction        F) human             G) result in          H) separated
I) cleared            J) leave             K) Finally            L) correspondence
M) drained            N) In addition       O) adapted to
【S7】
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答案I
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