Scientists have discovered a powerful antibiotic in the blood stream of giant pandas that can destroy bacteria. The Chinese rese

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问题     Scientists have discovered a powerful antibiotic in the blood stream of giant pandas that can destroy bacteria. The Chinese researchers discovered the【C1】________known as cathelicidin-AM, after【C2】________the panda’s DNA It’s thought that the antibiotic is【C3】________by the bear’s immune system in order to protect them from infections.
    The scientists found that cathelicidin-AM killed bacteria in less than an hour【C4】________other antibiotics took more than six hours. They now want to develop the substance as a new drug to fight superbugs.
    The【C5】________bears, of which there are just 1,600 in the wild, have become a symbol for conservation—and now there could be a new reason to try and protect them.【C6】________, scientists will not need to rely on the animal’s unreliable breeding ability to【C7】________the new antibiotic, as they have been able to make it artificially in the lab by decoding the genes to produce a small molecule known as a peptide.
    Dr Xiuwen Yan, who led the research at the Life Sciences College of Nanjing Agricultural University in China told the Daily Telegraph: "It showed potential antimicrobial activities against wide【C8】________of microorganisms including bacteria, both standard and drug-resistant【C9】________. Under the pressure of increasing microorganisms【C10】________drug resistance against conventional antibiotics, there is【C11】________need to develop new type of antimicrobial agents. Gene-encoded antibiotics play an important role in immune system against【C12】________microorganisms. They cause much less drug resistance than conventional antibiotics."
    Panda populations have decreased【C13】________the destruction of their natural habitat and bamboo food【C14】________in China and south east Asia.【C15】________to increase their numbers, including efforts at Edinburgh Zoo with resident pandas Tian Tian and Yang Guang, have been【C16】________for the extreme difficulty in getting them to breed in captivity.【C17】________in the wild, pandas【C18】________to breed easily, as the females only come into season once a year.
    It has been【C19】________that the millions of pounds spent in using expensive artificial breeding techniques could be put to better use on other conservation projects. And this new discovery is likely to【C20】________the case to save the endangered creatures.
【C4】

选项 A、for
B、after
C、unless
D、while

答案D

解析 前半句提到科学家们发现抗菌肽-AM能在不到一小时的时间内杀死病菌,后半句提到其他抗生素则需要六个小时以上,可以看出是在对比抗菌肽-AM和其他抗生素,因此空格处需要一个表示对比关系的连词。D项while“然而”符合逻辑。A项for“因为”,表示因果关系。B项after“在……之后”,表示先后顺序。C项unless“除非”,表示条件。这三项均不含有对比关系。
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