什么是条件状语从句

主要的有if, unless, as [so] long as等：

You can leave now if you like. 如果你愿意现在就可以走了。

As long as it doesn’t rain we can go. 只要不下雨，我们就可以去。

【注】除以上基本的引导条件状语从句的从属连词外，还有的动词尤其是其分词形式(如suppose, supposing, provided, providing等)和介词短语(如in case, on condition that等)也可用作连词表示条件：

In case I forget, please remind me about it. 万一我忘记，请提醒我一下。

I will come on condition (that) she is invited too. 如果邀请她来, 那我就来。

He may go with us provided [providing] he arrives in time. 他若及时到，就可以和我们一起走。

Suppose the boss saw you，what would he say? 如果老板看到你，他会怎样说?

Supposing he does not come, shall we go without him? 他若不来，是不是不带他去?

条件状语从句的时态

I’ll stay at home if it rains tomorrow. 要是明天下雨，我就呆在家里。

If you will wait for a moment, I’ll go and tell the manager that you are here. 请等一下，我去告诉经理说你来了。