虚拟语气

　　条件句有真实条件句和非真实条件句两种。真实条件句所表示的假设是可能发生或实现的，主句与从句皆用陈述语气；非真实条件句所表示的假设是不可能或不大可能发生或实现的，主句与从句皆用虚拟语气。下面，我们一起来学习虚拟语气在条件从句中的用法。

从句谓语形式 主句谓语形式 例句 表示与现在事实 相 反 动词的过去式（be 动词一般用were） would / should / could / might + 动词原形 If there were no air or water, there would be no living things on the earth.

If I knew his telephone number, I would tell you. 表示与过去事实 相 反 had +过去分词 would / should / could / might + have +过去分词 If he had come yesterday, I would have told him about the news. But he didn't. 表示与将来事实可能相 反 ① were to + 动词原形

②should +动词原形 would / should / could / might + 动词原形 If you were to succeed, everything might be all right.

If green plants should disappear some day, there should hardly be any life on the earth. 【拓展】