初中英语从句相关知识点讲解：目的状语从句
顾名思义，用来说明主句中谓语动词发生的目的的从句叫做目的状语从句。 表示目的状语的从句可以由 that(以便)，so that(以便)， in order that(为了;以便)，Lest(免得;唯恐)， for fear that(生怕;以免)等词引导;目的状语从句的谓语常含有may, might, can, could, should, would等情态动词。
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.
学习目的状语从句应注意以下两点：
(1)目的状语从句中常含有can,could,may,might,should等情态动词。 例如：
I got up early so that I could catch the first bus. 我起得很早，目的是为了赶上头班公共汽车。
(2)在口语中so可以引导目的状语从句。例如：
We'll sit nearer the front so we can hear better. 我们坐的靠前一点，因此，我们听得清楚一点。
1、in order that与in order to的区别：
in order that+从句 in order to+动词原形 ( in order to后面加的那个不叫目的状语从句，叫目的状语) 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.(他起床很早是为了赶上第一班 公共汽车)
目的状语从句的一个特点：由于目的都是未来的行为，所以从句中一般用表示未来可能性时态，比如上面句中的could。当然还可以用will,would,can,等 。
2、so that既可引导目的状语从句，也可以引导结果状语从句。
1)其引导结果状语从句时，so that翻译为“以至于...”，经常可以和so/such...that...转换，且从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)其引导目的状语从句时，从句只能放在主句之后，此时可以和in order that换用。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.
初中英语从句相关知识点讲解：条件状语从句
引导条件状语从句的连接词主要有：if(如果)、unless(除非)或 as long as(只要)等。unless在意思上等于if...not。
一、条件状语从句用法
1、引导条件状语从句最常用的连词是if,由if引导的条件状语从句表示在某种条件下某事很可能发生。如:
If you ask him, he will help you.如果你请他帮忙,他会帮你的。
If you fail in the exam, you will let him down.如果你考试不及格,你会让他失望的。
另外,if从句还表示不可实现的条件或根本不可能存在的条件,也就是一种虚拟的条件或假设,从句多用一般过去时或过去完成时。如: If I were you, I would invite him to the party.如果我是你,我会邀请他参加聚会。
2、unless = if...not. 除非,若不,除非在……的时候
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,比赛将照常进行。
3、so/as long as只要
例句;You may borrow my book as long as you keep it clean. 只要你保持书的清 洁，你就可以把我的书借去。
So long as you’re happy, it doesn’t matter what you do. 只要你高兴，你做什么都没有关系。
二、时态问题
在条件状语从句中，要注意“主将从现”的规定，即主句用一般将来时，从句用一般现在时表示将来时。例句： I will come to see you if I have time. 我有时间，我就来看你。
初中英语从句相关知识点讲解：原因状语从句
原因状语从句应注意的问题
1、because , since , as , for,辨析
1)because语势最强，用来说明人所不知的原因，回答why提出的问题。当原因是显而易见的或已为人们所知，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引导的从句如果放在句末，且前面有逗 号，则可以用for来代替。但如果不是说明直接原因，而是多种情况加以推断，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的区别：通常情况下，as引导的从句在主句前，for引导的从句在主句后。例： As the weather is cold, I stay at home.(同义句) I stay at home, for the weather is cold.
2、because习惯上不与so连用
汉语习惯上说“因为…所以…”，但英语习惯上却不能将 so与because 连用：
正：Because it was raining, we stayed at home. / It was raining, so we stayed at home.
误：Because it was raining, so we stayed at home. 因为下雨，所以我们呆在家里。
3、because 从句与 because of短语的转换
Because引导的原因状语从句有时可与because of 短语转换，because of后加的原因可以为好或坏 ，但最正规的还是because。
He can’t come because he is ill. / He can’t come because of his illness. 他因病不能来。
I said nothing about it because his wife was there. / I said nothing about it because of his wife’s being there. 因为他妻子在那儿，我对此事只字未提。
