题目内容：

I can't find my umbrella.You __________it in the office.
A.must have forgotten B.must have left C.must leave D.must forget

优质解答

整句意思：我找不到我的雨伞了.你一定是把它落在办公室了.
根据句意,A和D的选择不符合句意,故先排除.
现在看B和C,leave意思是遗留.符合句意.
但是你把雨伞遗留在办公室已经是发生过的事情了,所以用完成时.
so the correct answer is B.
Thank you!