一、if
从句 主句
与现在相反 did/were would/could/should/might do
与过去相反 had done would/could/should/might have done
did/were;
与将来相反 were to do; would/could/should/might do
should do
1. If I were a bird, I would fly to you. _____
2. If he had followed my advice, he would have succeeded. _____
3. If it rained/were to rain/should rain, I would stay here. _____
注意:
(1). 在if引导的虚拟语气中，从句部分如果有had, were, should, 可以省略if,
将had, were, should 提前。
将以上三句改为倒装
