虚拟语气与将来相反，从句中有三种情况，那我哪知道什么情况用哪种？

主句都一样，只是从句有区别。请看：与现在事实相反：从句动词用：did/were; 主句动词用：would do/ be 与将来事实相反：从句动词用：should(were to) do /be 主句动词用：would do/ be 用在以if引导的非真实条件状语从句中，从句和主句皆须用虚拟语气。从句和主句动词的搭配形式，通常为：与现在事实相反：从句动词用：did/were; 主句动词用：would do/ be 与过去事实相反：从句动词用：had done/been 主句动词用：would have done/ been 与将来事实相反：从句动词用：should(were to) do /be 主句动词用：would do/ be 三种基本形态（这是基础，建议牢记下面的例句，争取能脱口而出） 与现在事实相反：If I had enough money, I would buy a book. 与过去事实相反：If I had had enough money, I would have bought a book. 与将来事实相反：If I were to have enough money, I would buy a book. If I should have enough money, I would buy a book.