2. 外语
  3. Should we care if over 150 known species of animals have【C1】______from the earth in the last fifty years? Should we be concerned

Should we care if over 150 known species of animals have【C1】______from the earth in the last fifty years? Should we be concerned

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问题     Should we care if over 150 known species of animals have【C1】______from the earth in the last fifty years? Should we be concerned that there are【C2】______thousands of species whose very existence is【C3】______endangered—largely because of our activities?【C4】______, after all, is the natural end of populations. Species are born, then【C5】______, and then die. Some live a【C6】______time, perhaps millions of years; some die more quickly. We have【C7】______the extinction of many species we know about, and we have undoubtedly sealed the【C8】______of others. In fact, there are undoubtedly many other species that have lived among us during our time on earth, but that have disappeared as a(n)【C9】______of our activities without our ever having known they existed.
    It is hard to explain the rationale of many of us who are concerned about such matters. I have never seen a sea whale,【C10】______I don’t want them to become extinct. Moreover, I felt this way long before I understood anything about how they might be an important part of an ecosystem. Possibly such feelings merely reflect the cultural attitude that it is ""nice"" to wish other living things well; thus, the attitude is【C11】______.I feel nice.
    There are, of course, more rational reasons for【C12】______the extermination of any species. For one thing, the kind of attitude that encourages or sanctions the destruction of other species is a threat【C13】______our own wellbeing. If such an attitude exists, we ourselves might【C14】______victim to it. Living things(including us)might be expected to fare better where there is【C15】______for life. The extinction of other species could also threaten us【C16】______by simplifying the system of which we are a part or by destroying parts of the ecosystem【C17】______which we directly rely. For example, if we continue to poison the oceans【C18】______we are willing to believe only a few bottom dwellers are affected, we might【C19】______overstep some critical threshold and trigger the wholesale death of plankton, thus finding ourselves without a major【C20】______of the world’s food and with our oxygen supplies dwindling."
【C18】
选项 A、because
B、as if
C、and
D、even
答案A
解析 句子前后为因果关系，所以用because引导这一从句，大意是说“因为我们相信我们的行为只影响了海底的几种生物，所以我们便持续污染海洋”。
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