虚拟条件句的三种基本类型

条件句有真实条件句和非真实(虚拟)条件句两种。真实条件句所表示的假设是有可能发生的，而非真实条件句则通常表示一种假想，与事实相反或不大可能会发生：

If I have time, I will go with them. 假若我有时间，我就同他们去。(陈述语气)

If I were you, I would go with them. 假若我是你，我就同他们去。(虚拟语气)

虚拟条件句的三种基本类型

一、与现在事实相反

若与现在事实相反，条件从句的谓语用过去式(be通常用were)，主句谓语用“should (would, could, might)+动词原形”：

If you took a taxi，you’d get there quicker. 如果你坐出租车去，你可以快一点到那里。(但你不坐)

If I knew her number I could ring her up. 要是我知道她的电话号码，我就可以给她打电话了。(可惜我不知道)

二、与过去事实相反

若与过去事实相反，条件从句的谓语用过去完成时(had+过去分词)，主句谓语用“should (would, could, might)+have+过去分词”：

If I’d left sooner，I’d have been on time. 要是我早点动身，我就准时到了。(但我动身太迟了)

If we had found him earlier we could have saved his life. 要是我们当时早点找到他的话，我们就可以救活他。(可惜我们找到他太晚了)

三、与将来事实相反

若与将来事实相反，条件从句的谓语用过去式(be通常用were)，主句谓语用“should (would, could, might)+动词原形”：

If he went，would you go too? 如果他去，你也去吗?(大概他不会去)

If I asked him，I’m sure he’d help us. 如果我向他提出要求，肯定他会帮助我们。(不过我不打算这样做)