Question

【题目】It might have saved me some trouble ______ the schedule.
A.did I know
B.have I known
C.do I know
D.had I known

Answer 1

【答案】D
【解析】句意：如果我早知道日程安排，可能会省去我一些麻烦。根据might have saved可知主句是对过去的虚拟，从句应用if I had known与主句保持一致。if虚拟条件句中含有had时，可将if省去，同时将had提前构成倒装结构。故选D项。