_____ that air conditioners cause so much pollution, I would never have bought o

题干

_____ that air conditioners cause so much pollution, I would never have bought one.

A．Had I known

B．I had known

C．Were I to know

D．Did I know

上一题下一题 0.85难度单项选择更新时间:2010-12-20 11:16:39

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