题目

 Do you know ______in Japan? A. when nuclear(核) accidents happened   B. when did nuclear accidents happen C. when nuclear accidents happen        D. when do nuclear accidents happen 答案：A 【解析】考查点：宾语从句。解题思路：宾语从句的语序用陈述句语序，故排除B、D选项，主句是一般现在时态，从句的时态根据情况而定，故从句用一般过去时态。故选A。

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