题目内容
18.The students__________ their experiments when a stranger broke into the lab.( )A. | had been doing | B. | have been doing | C. | would be doing | D. | were doing |
分析 当这个陌生人闯入实验室的时候,这些学生们正在做实验.
解答 答案:D.根据when a stranger broke into the lab可知当这个陌生人闯入实验室的时候,这些学生们正在做实验,所以谓语动词do用过去进行时,故答案为D.其他选项表示的时态分别是:A、过去完成进行时 B、现在完成进行时 C、过去将来进行时.
点评 考查过去进行时.过去进行时表示过去的某个点正在进行的动作,而将来进行时表示将来的某个点正在进行的动作.

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