条件句类型及用法有哪些

条件句有真实条件句和非真实条件句两种，真实条件句所表的假设是可能发生或实现的，句中的条件从句与结果主句皆用直陈语气。条件句属于英语的概念，而英语已经发展了1400多年。英语的最早形式是由盎格鲁-撒克逊人移民于5世纪带到英国的一组西日耳曼语支（Ingvaeonic）方言，被统称为古英语。

如:

（1）Oil floats if you pour it on water.你如把油倒在水里，油就浮起来。

（2）If I have enough money next year,I will go to Japan.假若明年我有钱，我就去日本。非真实条件句所表的假设则是不可能或不大可能发生或实现的，句中的条件句与结果主局皆须用虚拟语气。现将用于非真实条件句中的虚拟时态列表如下(注：美国的结果主局，不管什么人称皆常用would)：与现在事实相反：从句，If I（we，you,he,they）+动词过去式（be的过去式用were）；结果主句：(I/we+should,you/he/they+would)+动词原形，如：If we left now,we should arrived in good time.假如我们现在就走的话，我们就会及时到达。If I were you,I would refuse the money.假如我是你的话，我就不会要那钱。Even if he had the money,he wouldn`t buy it.他即使有钱也不会卖它。与过去事实相反：从句，If I（we，,he,they）you+had+过去分词；结果主句：/we+should,(I you/he/they+would)+have+过去分词，如：We would`ve dropped by if we had had time.假若我们有时间的话，我们就会顺道拜访了。I wouldn`t have known what these were for if I hadn`t been told.假如别人不告诉我，我就不会知道这些东西是干什么的了。但虚拟式were也可表示与过去事实相反。If I were not busy,I would have come.假如我不忙，我就会来了。表过去时间的假设亦可用虚拟式，should have+过去分词。