引导原因状语从句的连词

1）引导原因状语从句的连词主要有because, as, since:
because:
Because it was wet he took a taxi. 由于下雨他叫了一辆出租车。
He was worried because he hadn't had any letter from her. 他很担忧因为他没收到过她一封信。
Why aren't you coming with us?——Because I have got a bad headache. 你为什么不和我们一块去？——因为我头很疼。
as:
As David had a passion for walking, we started off on foot. 由于大卫喜欢走路，我们就步行出发了。
We don't go there much now, as we are going away so soon. 我们现在不常去那儿，因为我们不久就要离开了。
As you're sorry, I'll forgive you. 既然你悔悟了，我就原谅你。
since:
Since they've obviously forgotten to phone me, I'll have to telephone them. 由于他们显然忘了给我打电话，只好由我来打给他们。
Since you can't answer my questions, I'll have to ask someone else. 既然你回答不了我的问题，我只好问别人。
He was not prepared for the question, since he had not made up his mind. 对这问题他没有思想准备，因为他还没拿定主意。
2）还有一些表示原因的状语从句由seeing(that), considering(that)或now that等引导：
Seeing that he's been ill all weak, he's unlikely to come. 鉴于他已病了一个星期，他来的可能性不大。
We could have a joint party, seeing your birthday is the same day as mine. 由于你我的生日在同一天，我们可以办一个联合晚会。
Considering he has only just started, he knows quite a lot about it. 考虑到他刚刚开始，对此他算是知道得很多了。
Considering you've only been studying for a year, you speak English very well. 考虑到你学英语才一年，你英语讲得算是很好的。
Now that you have the chance you had better avail yourself of it. 既然你有了机会，你最好利用起来。
Please don't try to back out now that everything has been arranged. 现在一切都安排好了，请不要打退堂鼓。
Now you're here, you may make yourself useful. 你已经来了，不妨帮帮忙。
seeing, considering, now that都可以看作连词。
3）许多用在形容词后的that从句也起原因状语的作用（that有时可省略）：
She was glad that she had controlled herself. 她很高兴控制住了自己。

He felt ashamed that he had done so little. 他为自己做得这么少而感到惭愧。

I am awfully sorry that this has happened. 发生了这事我非常遗憾。

I'm very pleased you've decided to come. 你决定来我很高兴。

I am disappointed that they cannot come. 他们不能来我很失望。

I am surprised I didn't see that before. 我很吃惊我以前没看到这一点。