____their homework , the children went for a walk .
问题描述：
____their homework , the children went for a walk .
a.when they were doing b.after they have done
c.Having doned .They had done
请选择帮忙解释一下
答
c
第一,现在完成时表示作完作业的动作在出去散步的动作之前,而出散步用的是过去时,做作业当然用现在完成时.
第二,主语是the children,前面的做作业的动作由主语完成,表示主动,所以用主动语态,因此,用hanving表示主动语态,另外,having也表示引导一个现在分词短语.