题干

结合以下图表分析,有关说法正确的是(  )
抗菌药物
青霉素
环丙沙星
红霉素
利福平
抗菌机理
抑制细菌细胞壁的合成
抑制细菌DNA解旋酶的活性(可促进DNA螺旋化)
能与核糖体结合,阻止了其与RNA结合
抑制RNA聚合酶的活性

A:①~⑤可发生在人体健康细胞中

B:青霉素和利福平能抑制DNA的复制

C:结核杆菌的④和⑤都发生在细胞质中

D:环丙沙星、利福平和红霉素分别能抑制细菌的①②和③过程

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答案(点此获取答案解析)

D

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    New York is one of the last large American cities to have some of its policemen on horseback. The New York police have 170 horses working in certain parts of the city. The horses are expensive to feed, but it is even more expensive to look after them. Because the horses must walk on the streets, they need special horseshoes. In fact, they need more than 8,000 of them each year. Every police horse in New York gets new shoes every month. Keeping these shoes in good repair is the job of six blacksmiths. There are only about thirty-five of these blacksmiths in the whole United States.

    The cost of shoeing a horse is between twenty dollars and thirty-five dollars, and it takes a good blacksmith two or three hours to do the job.

    A blacksmith's job is not an easy one. He must be able to shape a shoe from a piece of metal and then fit it to the horse's foot. The blacksmith must bend over all the time when he is fitting the shoe and must hold the weight of the horse's leg while he works. Clearly, a blacksmith must be very strong. But even more important, he must be able to deal with horses---for before the blacksmith can begin his work, he has to get the horse to lift its leg.

   One of the blacksmiths in New York is James Corbin. He came to the country from Ireland in 1948. He not only makes horseshoes for the police but also works for a group of horse owners near the city. Corbin became interested in blacksmithing because his father did it, and, as he puts it, “It's a good way to make a living.”