2.与过去事实相反的虚拟语气,基本结构为:主语+动词的过去完成时+其他成分+if+should/would/could...+have done+其他成分。例如: If the weather had been better,we could have had a picnic.But it ___ all day. A.rained B.rains C.has rained D.is raining 解析 句...