條件狀語從句主要由if, unless, as [so] long as, in case 等引導。如：
一、由if引導
Don’t be anxious if I’m late. 如果我來遲了，不要著急。
I’ll fire if you come any nearer. 再走近一點我就開槍了。
Could you endure poverty if I went away? 我要是離開了你能忍受貧窮嗎？
You can ask my mother if you don’ t believe me. 你如果不相信我可以問我母親。
If anyone calls tell them I’m not at home. 要是有人打電話來，就說我不在家。
You could get a better job if you spoke a foreign language. 如果你能講外語，你可以找到好點的工作。
二、由unless引導
You will fail unless you work hard. 你若不努力就會失敗。
I won’t write unless he writes first. 如果他不先寫信，我也不寫。
Don’t come unless I telephone. 除非我給你打電話否則不要來。
We’ll have the outing tomorrow unless it rains. 我們明天去郊游除非是下雨。
Unless you wear boots you may be bitted by snakes. 若不穿靴子你可能被蛇咬。
I shouldn’t dream of going unless you wanted rIIe. 除非要我去，否則我不會想去。
Unless I parted from Sheila, l could not keep up that struggle. 如果我不和希拉分手我就沒法堅持這一斗爭。
三、由as [so] long as引導
As long as you need me, I’ll stay. 只要你需要我，我就留下。
I’m happy as long as you are happy. 只要你快樂我就快樂。
I shall love you as long as I have breath. 只要我還有一口氣，我就會愛你。
So long as you make Ruth happy I’m content. 只要你讓魯思高興我就滿意了。
So long as you make Ruth happy I’m content. 只要你讓魯思幸福我就滿足了。
You can take my cal so long as you drive carefully. 只要你開車小心，我可以把車借給你。
As long as you understand, we shall say no more about it. 只要你能理解，我們就不說什么了。
You may use the room so long as you keep it clean. 你可以使用這個房間，只要你能保持干凈。
四、由in case 引導
In case I forget, please remind me about it. 萬一我忘記，請?zhí)嵝盐乙幌隆?BR> In case he arrives before I get back, please ask him to wait. 如果他在我回來以前到，請讓他等等我。
【注】在條件狀語從句中，通常要用一般現在時表示將來意義，而不能直接使用將來時態(tài)。不過，有時表示條件的 if之后可能用 will，但那不是將來時態(tài), 而是表示意愿或委婉的請求(will為情態(tài)動詞)。如：
If you will wait a moment, I’ll fetch the money. 請等一下，我就去拿錢。
一、由if引導
Don’t be anxious if I’m late. 如果我來遲了，不要著急。
I’ll fire if you come any nearer. 再走近一點我就開槍了。
Could you endure poverty if I went away? 我要是離開了你能忍受貧窮嗎？
You can ask my mother if you don’ t believe me. 你如果不相信我可以問我母親。
If anyone calls tell them I’m not at home. 要是有人打電話來，就說我不在家。
You could get a better job if you spoke a foreign language. 如果你能講外語，你可以找到好點的工作。
二、由unless引導
You will fail unless you work hard. 你若不努力就會失敗。
I won’t write unless he writes first. 如果他不先寫信，我也不寫。
Don’t come unless I telephone. 除非我給你打電話否則不要來。
We’ll have the outing tomorrow unless it rains. 我們明天去郊游除非是下雨。
Unless you wear boots you may be bitted by snakes. 若不穿靴子你可能被蛇咬。
I shouldn’t dream of going unless you wanted rIIe. 除非要我去，否則我不會想去。
Unless I parted from Sheila, l could not keep up that struggle. 如果我不和希拉分手我就沒法堅持這一斗爭。
三、由as [so] long as引導
As long as you need me, I’ll stay. 只要你需要我，我就留下。
I’m happy as long as you are happy. 只要你快樂我就快樂。
I shall love you as long as I have breath. 只要我還有一口氣，我就會愛你。
So long as you make Ruth happy I’m content. 只要你讓魯思高興我就滿意了。
So long as you make Ruth happy I’m content. 只要你讓魯思幸福我就滿足了。
You can take my cal so long as you drive carefully. 只要你開車小心，我可以把車借給你。
As long as you understand, we shall say no more about it. 只要你能理解，我們就不說什么了。
You may use the room so long as you keep it clean. 你可以使用這個房間，只要你能保持干凈。
四、由in case 引導
In case I forget, please remind me about it. 萬一我忘記，請?zhí)嵝盐乙幌隆?BR> In case he arrives before I get back, please ask him to wait. 如果他在我回來以前到，請讓他等等我。
【注】在條件狀語從句中，通常要用一般現在時表示將來意義，而不能直接使用將來時態(tài)。不過，有時表示條件的 if之后可能用 will，但那不是將來時態(tài), 而是表示意愿或委婉的請求(will為情態(tài)動詞)。如：
If you will wait a moment, I’ll fetch the money. 請等一下，我就去拿錢。