It_________five or ten years before the new medicine is tested on human beings.A.will take B.took C.takes D.has taken选A

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It_________five or ten years before the new medicine is tested on human beings.A.will take B.took C.takes D.has taken选A
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It_________five or ten years before the new medicine is tested on human beings.A.will take B.took C.takes D.has taken选A
It_________five or ten years before the new medicine is tested on human beings.
A.will take B.took C.takes D.has taken选A

It_________five or ten years before the new medicine is tested on human beings.A.will take B.took C.takes D.has taken选A
句子的意思是:在人类身上试用这些药物之前,还需要5或10年,很明显,需要用到一般将来时.
这里只有选项A符合条件.
(主句一般将来时,从句一般现在时)

B因为它是过去时

A 考查动词时态

是想问为什么吗?It will +一段时间+before可以看成是一个句型。理解的话,画个数轴应该会便于理解,这种新药是在五年或者十年后被试用,即现在距离被试用还有五到十年,所以是个将来的时态。这是我们两个英语老师讲的方法,挺有效的