Newton was playing under an apple tree---an apple fell onto

问题描述:

Newton was playing under an apple tree___an apple fell onto his head.
A.when B.while C.after D.before
请问选择哪一个,及分别说出每个为什么对与错.
1个回答 分类:综合 2014-09-26

问题解答:

我来补答
选A when在这里是这时的意思 while应用于进行时的句子 前面有was playing,所以不能选后两个.
 
 
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