Afterwehadpaintedthewallwhite

发布时间：2020-07-28 08:14:18

After we had painted the wall white he ________ some green dots on the wall.A.had droppedB.happened to dropC.have droppedD.happened to have dropped

网友回答

B解析happen to do“碰巧”而happen to have done指发生在动作paint之前，故用不定式的一般式。
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