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When and where this took place still unknown.A. is B. has C. were D. are

编辑:chaxungu时间:2026-04-27 02:48:01分类:高中英语题库

【题目】 When and where this took place _____ still unknown.

A. is B. has C. were D. are

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【答案】A

【解析】

试题分析:考查系动词。句意:这个发生在何时何地还不清楚。就近原则,无论when where哪个在前均用单数形式,故选A。