现在：If I were you,I would continue.
(did/were,would/should/could/might+动词原形）
过去：If you had worked harder,you might have pass the exam.
(had+done,would/should/could/might+done)
将来：If I shoud come tomorrow,Iwould bring the book to you.
(did/ should+动词原形 / were to+动词原形,would/should/could/might+动词原形）
句子都大同小异的,用法给你,自己继续造吧!