1. because + 句子
常表示直接因果关系
注意because不可与so连用
I left because I was afraid.
我离开是因为我害怕。
We were late because our car wouldn't start.
我们迟到是因为我们的车启动不了。
2. because of + 短语
We didn't go shopping because of bad weather.
我们没去逛街是因为天气不好。
Because of you, we missed the train.
因为你，我们错过了火车。
3. since / as +句子
常表示鉴于已知事实或已知理由，有“既然”之意
Since /As you are all here, let’s have a meeting.
因为我们大家都在这里，所以我们开会吧。
Since/As we are friends, we should help each other.
因为我们是朋友，所以我们应该互相帮助。
4. for+句子
用于对之前所做出的陈述进行补充说明部分原由，置于后句，for前有逗号，通常用于正式文体，现较少用
She was certainly at the station, for I saw them.
她确实在车站，因为我看见她了。
I don't know whether he is tall or short, for I have never seen him.
我不知道他是高是矮，因为我没见过他。
拓展内容
想要拓展的同学，可以看看。其他常见的表示“因为”的词，阅读里可能会见到。
1.seeing that/ considering that + 句子
Seeing that/ Considering that we are in trouble, you may
as well help me.
因为我们有麻烦，所以你就帮帮我吧。
2.due to / on account of + 短语
The bus was late due to/ on account of bad weather.
巴士晚点是因为天气不好。
3. in view of / owing to/ as a result of / for the reason of +短语
In view of / Owing to the fact that your payment is late, you'll have to pay a fine.
因为你没有按时付款，所以你必须缴纳罚款。