一、原因状语从句：常用的引导连词有because,as和since。

一、原因状语从句：常用的引导连词有because , as和
since。

一、原因状语从句:常用的引导连词有because , as和since。

三者的区别是:在
回答问题的时候，使用because;对于显而易见的原因，常用as或since;as和since的从句常放在主句之前，而because的从句常放在主句之后。

eg.
Why did you go? I went because Tom told me to go.
你为何去,那是因为汤姆叫我去。

He was angry not because we were late but because we made a noise.
他很生气不是因为我们来迟了，而是因为我们弄出了声音。

As it was raining hard, we had to be indoors. 由于雨太大，我们只好呆在家里。

Since you feel ill, you’d better not go to work. 既然你感觉不舒服，你最好不要
去上班了。

注意:because是连词，引导原因壮语从句，不能与so连用;二because of 是短
语介词，只能引导表示原因的短语。

二、结果状语从句:
引导结果状语从句的常用连词有:so…that/such/…that(如此……以至于);so that(结果)。

常用句型为:
so +形容词/副词 + that
so + 形容词 + a/an + 单数可数名词 + that
such + a/an + 形容词 + 单数可数名词 + that
such + 形容词 + 复数可数名词 + that
such + 形容词 + 不可数名词 + that
He spoke so fast that I couldn’t follow him.
他讲得太快我跟不上。

It was such a good day(=It was so good a day) that we all went swimming.
天气那么好，我们都去游泳了。

The film was so wonderful that everyone was deeply moved.
电影是如此精彩，所有人都被深深打动了。

so…that与such…that之间的转换既为 so与such之间的转换。

The boy is so young that he can't go to school.
He is such a young boy that he can't go to school.
注意:“so + many/much/ little(少)/few + 名词+ that”是习惯用法。

三、目的状语从句
引导目的状语从句常用的连词有: 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)。

【例】
Say it louder(so)that everyone can hear you. 大声说，以便大家都能听到你。

I am telling you that lest you should make a mistake.
我告诉你这一点，以免你搞错。

学习目的状语从句应注意以下两点:
(1)目的状语从句中的谓语动词常用 may(might)，can(could)，should等情
态动词。

【例】
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】
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。

注:目的状语从句可以用动词不定式来替换做目的状语
eg.
inorderto,,
,,to,,We work harder than usual finish it in a week. 我们比平常加倍努力工作以便在一周内完成工作。