英语中表示假设的句子主要是虚拟语气，其表示方式有：

1.以if条件从句为虚拟语气标志：

与现在事实相反 从句时态用一般过去时（be用were),主句用过去将来时

例如：If I were you, I would finish homework first.

与过去事实相反 从句用过去完成时，主句用过去将来完成时

例如：If I had gone there, I would have bought two tickets.

与将来事实相反 从句用一般过去时或过去将来时，主句用过去将来时

例如：If he had/would have time, he would come to your birthday party tomorrow.

2.以even if/though让步从句为虚拟语气标志 主从句时态同if条件从句相同

例如：He might give you more help, even though he were/was very busy.

3.以as if/though引导的表语从句或状语从句为虚拟语气标志 主从句时态同if条件从句相同

例如：It seems as if he had known the news.

4.以wish后的宾语从句为虚拟语气标志

与现在事实相反 从句时态用一般过去时（be用were)

例如：I do wish I knew more about the subject.

与过去事实相反 从句用过去完成时

例如：I wish I had seen you yesterday.

与将来事实相反 从句用过去将来时

例如：I wish you wouldn't smoke any more.