题目内容：

    When discussing the causes of animal endangerment, it is important to understand that individual species are not the only factors involved in this difficult situation. Endangerment is a broad _________, one that involves the habitats and environments where species live and interact with one another. Although some measures are being taken to help specific cases of endangerment, the universal problem cannot be solved until humans _________ the natural environments where endangered species live. There are many reasons why a particular species may become endangered, but habitat destruction is on top.

Our planet is continually changing, causing habitats to be altered and modified. Natural changes tend to occur at a(n) _________ pace, usually causing only a slight _________ on individual species. However, when changes occur at a fast pace, there is little or no time for individual species to _________ and adjust to new situations. This can create disastrous results, and for this reason, rapid habitat loss is the primary cause of species endangerment. The strongest _________ in rapid habitat loss are human beings. Nearly every region of the earth has been affected by human activity, particularly during this past century. The loss of microbes in soils that _________ supported tropical forests, the extinction of fish and various aquatic species in polluted habitats, and changes in global climate brought about by the _________ of greenhouse gases are all results of human activity.

It can be difficult for an individual to _________ the effects that humans have had on specific species. It is also hard to identify or ____________ human effects on individual species and habitats, especially during a human lifetime. But it is quite ____________ that human activity has greatly contributed to species endangerment. ____________, although tropical forests may look as though they are thick and healthy; they are____________ highly susceptible (易受影响的) to destruction. This is because the soils in which they grow ____________ nutrients. It may take centuries to re-grow a forest that was cut down by humans or destroyed by fire, and many of the world’s severely threatened animals and plants live in these forests. If the current rate of forest ____________ continues, huge quantities of plant and animal species will disappear.

1.A.remark B.issue C.project D.experiment

2.A.worsen B.protect C.seek D.ignore

3.A.extreme B.favorable C.gradual D.rapid

4.A.command B.spirit C.impact D.expectation

5.A.react B.boost C.express D.announce

6.A.sports B.meanings C.forces D.crimes

7.A.usually B.formally C.freely D.formerly

8.A.escape B.goal C.release D.origin

9.A.update B.recognize C.cover D.remind

10.A.predict B.devote C.struggle D.transfer

11.A.obvious B.vital C.contemporary D.selfish

12.A.In short B.In a word C.As a result D.For example

13.A.naturally B.completely C.fully D.actually

14.A.contain B.lack C.reduce D.limit

15.A.growth B.loss C.extension D.planting