具有快速杀菌作用的药物是：
A．四环素B．氯霉素C．二者皆是D．二者皆不是
参考答案：D
Can't you see your problem ____?Have some patience, please.
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A. is being discussed
B. was being discussed
C. is discussed
D. has been discussed
农田灌溉需要用水泵抽水，每分钟用水380kg，所用水需要从14m深的井里抽取，则水泵的额定功率至少是______（取g=10m/s2）
