Has he finished his homework yet?Yes,he _____ it an hour ago.A has done B did C had done D was doing 选哪个?为什么?

Has he finished his homework yet?Yes,he _____ it an hour ago.A has done B did C had done D was doing 选哪个?为什么?
Has he finished his homework yet?Yes,he _____ it an hour ago.
A has done B did C had done D was doing 选哪个?为什么?

Has he finished his homework yet?Yes,he _____ it an hour ago.A has done B did C had done D was doing 选哪个?为什么?
B
问某人是否做过某事/某事是否已发生【现在完成】
问某事何时发生的用一般过去时,夲句后面有an hour ago一般过去时的标志.

答案：B did
典型标志是ago，这是一般过去时态的标志。

本来，ago是用过去时的标志，但因为前面的疑问句用的是完成时，所以回的就应该是过去完成时，那么标准答案就是C了

C 。已经做完了，用完成时态，一个小时之前完成了，用过去完成时。
理解请采纳。