初中英語從句相關(guān)知識點講解：目的狀語從句
顧名思義，用來說明主句中謂語動詞發(fā)生的目的的從句叫做目的狀語從句。 表示目的狀語的從句可以由 that(以便)，so that(以便)， in order that(為了;以便)，Lest(免得;唯恐)， for fear that(生怕;以免)等詞引導(dǎo);目的狀語從句的謂語常含有may, might, can, could, should, would等情態(tài)動詞。
例如：You must speak louder so that /in order that you can be heard by all.
He wrote the name down for fear that(lest) he should forget it.
Better take more clothes in case the weather is cold.
學(xué)習(xí)目的狀語從句應(yīng)注意以下兩點：
(1)目的狀語從句中常含有can,could,may,might,should等情態(tài)動詞。 例如：
I got up early so that I could catch the first bus. 我起得很早，目的是為了趕上頭班公共汽車。
(2)在口語中so可以引導(dǎo)目的狀語從句。例如：
We'll sit nearer the front so we can hear better. 我們坐的靠前一點，因此，我們聽得清楚一點。
1、in order that與in order to的區(qū)別：
in order that+從句 in order to+動詞原形 ( in order to后面加的那個不叫目的狀語從句，叫目的狀語) 例如：
He got up early in order to take the first bus.
= He got up early in order that he could take the first bus.(他起床很早是為了趕上第一班 公共汽車)
目的狀語從句的一個特點：由于目的都是未來的行為，所以從句中一般用表示未來可能性時態(tài)，比如上面句中的could。當(dāng)然還可以用will,would,can,等 。
2、so that既可引導(dǎo)目的狀語從句，也可以引導(dǎo)結(jié)果狀語從句。
1)其引導(dǎo)結(jié)果狀語從句時，so that翻譯為“以至于...”，經(jīng)�？梢院蛃o/such...that...轉(zhuǎn)換，且從句只能放在主句之后。如：He got up late so that he was late for school. = He got up so late that he was late for school.
2)其引導(dǎo)目的狀語從句時，從句只能放在主句之后，此時可以和in order that換用。如：He got up early so that he could take the first bus. = He got up early in order that he could take the first bus.
初中英語從句相關(guān)知識點講解：條件狀語從句
引導(dǎo)條件狀語從句的連接詞主要有：if(如果)、unless(除非)或 as long as(只要)等。unless在意思上等于if...not。
一、條件狀語從句用法
1、引導(dǎo)條件狀語從句最常用的連詞是if,由if引導(dǎo)的條件狀語從句表示在某種條件下某事很可能發(fā)生。如:
If you ask him, he will help you.如果你請他幫忙,他會幫你的。
If you fail in the exam, you will let him down.如果你考試不及格,你會讓他失望的。
另外,if從句還表示不可實現(xiàn)的條件或根本不可能存在的條件,也就是一種虛擬的條件或假設(shè),從句多用一般過去時或過去完成時。如: If I were you, I would invite him to the party.如果我是你,我會邀請他參加聚會。
2、unless = if...not. 除非,若不,除非在……的時候
例如：Let's go out for a walk unless you are too tired.
=If you are not too tired, let's go out for a walk.
Unless it rains, the game will be played.除非下雨,比賽將照常進(jìn)行。
3、so/as long as只要
例句;You may borrow my book as long as you keep it clean. 只要你保持書的清 潔，你就可以把我的書借去。
So long as you’re happy, it doesn’t matter what you do. 只要你高興，你做什么都沒有關(guān)系。
二、時態(tài)問題
在條件狀語從句中，要注意“主將從現(xiàn)”的規(guī)定，即主句用一般將來時，從句用一般現(xiàn)在時表示將來時。例句： I will come to see you if I have time. 我有時間，我就來看你。
初中英語從句相關(guān)知識點講解：原因狀語從句
原因狀語從句應(yīng)注意的問題
1、because , since , as , for,辨析
1)because語勢最強(qiáng)，用來說明人所不知的原因，回答why提出的問題。當(dāng)原因是顯而易見的或已為人們所知，就用as或 since。
I didn’t go, because I was afraid.
Since /As the weather is so bad, we have to delay our journey.
2)由because引導(dǎo)的從句如果放在句末，且前面有逗 號，則可以用for來代替。但如果不是說明直接原因，而是多種情況加以推斷，就只能用for。例：
He is absent today, becaus e / for he is ill. He must be ill, for he is absent today.
3) as和for的區(qū)別：通常情況下，as引導(dǎo)的從句在主句前，for引導(dǎo)的從句在主句后。例： As the weather is cold, I stay at home.(同義句) I stay at home, for the weather is cold.
2、because習(xí)慣上不與so連用
漢語習(xí)慣上說“因為…所以…”，但英語習(xí)慣上卻不能將 so與because 連用：
正：Because it was raining, we stayed at home. / It was raining, so we stayed at home.
誤：Because it was raining, so we stayed at home. 因為下雨，所以我們呆在家里。
3、because 從句與 because of短語的轉(zhuǎn)換
Because引導(dǎo)的原因狀語從句有時可與because of 短語轉(zhuǎn)換，because of后加的原因可以為好或壞 ，但最正規(guī)的還是because。
He can’t come because he is ill. / He can’t come because of his illness. 他因病不能來。
I said nothing about it because his wife was there. / I said nothing about it because of his wife’s being there. 因為他妻子在那兒，我對此事只字未提。
