條件狀語(yǔ)從句主要由if, unless, as [so] long as, in case 等引導(dǎo)。如：一、由if引導(dǎo)Don’t be anxious if I’m late. 如果我來(lái)遲了，不要著急。I’ll fire if you come any nearer. 再走近一點(diǎn)我就開(kāi)槍了。Could you endure poverty if I went away? 我要是離開(kāi)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(wèn)我母親。If anyone calls tell them I’m not at home. 要是有人打電話來(lái)，就說(shuō)我不在家。You could get a better job if you spoke a foreign language. 如果你能講外語(yǔ)，你可以找到好點(diǎn)的工作。

二、由unless引導(dǎo)
You will fail unless you work hard. 你若不努力就會(huì)失敗。I won’t write unless he writes first. 如果他不先寫(xiě)信，我也不寫(xiě)。Don’t come unless I telephone. 除非我給你打電話否則不要來(lái)。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。Unless you wear boots you may be bitted by snakes. I shouldn’t dream of going unless you wanted me. 除非要我去，否則我不會(huì)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(méi)法堅(jiān)持這一斗爭(zhēng)。

三、由as [so] long as引導(dǎo)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(lè)我就快樂(lè)。I shall love you as long as I have breath. 只要我還有一口氣，我就會(huì)愛(ài)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(kāi)車(chē)小心，我可以把車(chē)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(shuō)什么了。 You may use the room so long as you keep it clean. 你可以使用這個(gè)房間，只要你能保持干凈 You may use the room so long as you keep it clean.

四、由in case 引導(dǎo)In case I forget, please remind me about it. 萬(wàn)一我忘記，請(qǐng)?zhí)嵝盐乙幌隆n case he arrives before I get back, please ask him to wait. 如果他在我回來(lái)以前到，請(qǐng)讓他等等我?！咀ⅰ吭跅l件狀語(yǔ)從句中，通常要用一般現(xiàn)在時(shí)表示將來(lái)意義，而不能直接使用將來(lái)時(shí)態(tài)。不過(guò)，有時(shí)表示條件的 if之后可能用 will，但那不是將來(lái)時(shí)態(tài), 而是表示意愿或委婉的請(qǐng)求(will為情態(tài)動(dòng)詞)。如：
If you will wait a moment, I’ll fetch the money. 請(qǐng)等一下，我就去拿錢(qián)。

?

?

?

?

?