英语语法点：英语条件状语从句及用法

引导条件状语从句的从属连词有if, unless (=if…not如果不……，除非), as/so long as(只要), while(=as long as只要), supposing (that)/provided /providing (that)(假如), in case(假使), on condition that(在……的条件下)等。如：

You can learn anything so long as you set your mind to learn it. 用心学本领，总能学到手。

I will go there tomorrow unless it rains.(=…if it doesn’t rain)除非下雨，否则我明天要去那儿。

He will do the work providing you pay him. 如果你能付费，他可以做这工作。

In case l forget，please remind me about it. 如果我忘了，请提醒我。

We’ll let you use the room on condition that you keep it clean and tidy. 我们可以让你使用这个房间，条件是你把它保持整洁。

注：条件状语从句和时间状语从句一样，从句的谓语动词不能用一般将来时态、过去将来时态或将来完成时，而要用相应的一般现在时、一般过去时和现在完成时态来替代。又如：

Tell me in case you get into difficulty. 遇到困难请告诉我。

Supposing he does not come, shall we go without him? 如果他不来，是不是不带他去?

但若从句谓语用了will或would，那will或would则是表示“愿意”的情态动词。如：

If you will go with me, I’ll wait for you. 如果你愿意等我，我们就帮你做这事儿。