目的状语从句

表示目的状语的从句可以由that, so that, in order that, lest, for fear that, in case等词引导，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.

原因状语从句

比较：because, since, as和for

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。

He is absent today, because / for he is ill.

He must be ill, for he is absent today.

地点状语从句

地点状语从句通常由where, wherever 引导。

Where I live there are plenty of trees.

我住的地方树很多。

Wherever I am I will be thinking of you.

不管我在哪里我都会想到你。