引導條件狀語從句的從屬連詞有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……的條件下)等。如：

You can learn anything so long as you set your mind to learn it. 用心學本領，總能學到手。

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

He will do the work providing you pay him. 如果你能付費，他可以做這工作。

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

We’ll let you use the room on condition that you keep it clean and tidy. 我們可以讓你使用這個房間，條件是你把它保持整潔。

注：條件狀語從句和時間狀語從句一樣，從句的謂語動詞不能用一般將來時態、過去將來時態或將來完成時，而要用相應的一般現在時、一般過去時和現在完成時態來替代。又如：

Tell me in case you get into difficulty. 遇到困難請告訴我。

Supposing he does not come, shall we go without him? 如果他不來，是不是不帶他去?

但若從句謂語用了will或would，那will或would則是表示“愿意”的情態動詞。如：

If you will go with me, I’ll wait for you. 如果你愿意等我，我們就幫你做這事兒。