同学你好，该知识点来自沪江网校《【Uni智能】雅思6.5分一站式VIP-初级【开学季专享签约现金奖励班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好，解答如下，希望能帮到你：
1.与现在事实相反
条件状语从句：一般过去式（be用were）
主句：would/should/could/might+动词原形
If I were you now, I would buy that coat.
2.与过去事实相反
条件状语从句：had+过去分词
主句：would/should/could/might+have+过去分词
If I had been you then，I would have bought that coat.
3.与将来事实相反
条件状语从句：一般过去时或should（were to）+动词原形
主句：would/should/could/might+动词原形
If I were /should be/were to be you tomorrow, I would buy that coat.