狀語(yǔ)從句：
用一個(gè)句子（從句）來(lái)作另一個(gè)句子（主句）的狀語(yǔ),用作狀語(yǔ)的句子就叫作狀語(yǔ)從句.作什么樣的狀語(yǔ)就叫什么類(lèi)型的狀語(yǔ)從句.例如：條件狀語(yǔ)從句就是用一個(gè)句子來(lái)作條件狀語(yǔ).
狀語(yǔ)從句的分類(lèi)：
（1）時(shí)間狀語(yǔ)從句
凡是從句都必須有引導(dǎo)詞,引導(dǎo)時(shí)間狀語(yǔ)從句的詞有when,before,after,until,as soon as,while 等.
（2）條件狀語(yǔ)從句
主要看一下由if引導(dǎo)的條件狀語(yǔ)從句.if 意為“如果”,引導(dǎo)條件狀語(yǔ)從句時(shí),表示假如有從句的動(dòng)作發(fā)生就（不）會(huì)有主句的動(dòng)作發(fā)生.例如：
If it doesn't rain tomorrow,we will go there by bike.如果明天不下雨,我們就騎自行車(chē)去那里.
If I get there early,I can see the doctor quickly.如果我早早地到那里,我就可以快點(diǎn)看病.
3）地點(diǎn)狀語(yǔ)從句用法要點(diǎn)
常用where（哪里）和wherever（無(wú)論哪里）eg.
Where there is a will,there is a way.有志者,事竟成.
We will go wherever the motherland need us most.我們要到祖國(guó)最需要的地方去.
（4）原因狀語(yǔ)從句用法要點(diǎn)
常用的引導(dǎo)連詞有because,as和since,三者的區(qū)別是：在回答問(wèn)題的時(shí)候,使用because；對(duì)于顯而易見(jiàn)的原因,常用as或since；as和since的從句常放在主句之前,而because的從句常放在主句之后.eg.
Why did you go?I went because Tom told me to go.你為何去?那是因?yàn)闇方形胰?
He was angry not because we were late but because we made a noise.
他很生氣不是因?yàn)槲覀儊?lái)遲了,而是因?yàn)槲覀兣隽寺曇?
As it was raining hard,we had to be indoors.由于雨太大,我們只好呆在家里.
Since you feel ill,you'd better not go to work.既然你感覺(jué)不舒服,你最好不要去上班了.
（5）目的狀語(yǔ)從句用法要點(diǎn)
常用的引導(dǎo)連詞有so that,that和in order that譯為：以便,為了,目的是.eg.
Please speak more slowly so that we can make full notes.請(qǐng)講慢一點(diǎn),以便我們能作詳細(xì)筆記.
I shall write down your address that I may not forget.我要把你的地址記下來(lái),以免忘記.
I sent the letter by air mail in order that it might reach him in time.這封信我以航空信發(fā)出,以便他能及時(shí)收到.
注：目的狀語(yǔ)從句可以用動(dòng)詞不定式來(lái)替換做目的狀語(yǔ).eg.
We work harder than usual finish it in a week.我們比平常加倍努力工作以在一周內(nèi)完成工作.
三、主句與從句時(shí)態(tài)一致的問(wèn)題.
在時(shí)間狀語(yǔ)從句和條件狀語(yǔ)從句中,主句和從句之間的時(shí)態(tài)一致問(wèn)題一般分下列兩種情況：
1.若主句是祈使句,或主句中有情態(tài)動(dòng)詞,或主句中謂語(yǔ)動(dòng)詞是一般將來(lái)時(shí),那么從句用一般現(xiàn)在時(shí)表示一般將來(lái)時(shí).例如：
Be careful when you cross the road.過(guò)馬路時(shí)要小心.
Put up your hand if you have any questions to ask.如果你們有問(wèn)題要問(wèn)的話,請(qǐng)舉手.
The traffic must stop when the lights are red.紅燈亮?xí)r,車(chē)輛必須停下.
2.若主從句謂語(yǔ)動(dòng)詞都是陳述過(guò)去,那么主從句都可以用一般過(guò)去時(shí).例如：
She could sing when she was four years old.她四歲的時(shí)候就會(huì)唱歌.