If I had learned it by heart ,I would have pass it !有的情况是省略了if所以句子的had提前就成了这样：Had I learned it by heart ,I would have pass it !蓄力语气中省略if的情况下都要倒装,不论是与现在事实相...Try as she might,Sue couldn't get the door open.这是一个虚拟语气的倒装句，原句是As she might try,Sue couldn't get the door open。这里面好像没有if可以省略啊。。。也要倒装么。。。这个就不是虚拟语气了，这个是as引导的让步状语从句，其概念为：as引导的让步状语从句必须倒装，如果动词货现在分词提前放在句首，谓语要补加助动词do/does/did,will等，如： Fail as he did , he would never give up .还有as引导的让步状语从句表语是名词的情况，这里就不多说明。我们来看这道题： 句子是as引导的让步状语从句，所以我们必须倒装。通过上面的概念可知，我们要把动词try提前。 于是就成了倒装的句子。