because, since, as, for 辨析

because, since, as, for 辨析

耀华中学 程岗

because, since, as, for这些词在实际使用中都可以用做连词，当作“因为”，“由于”来讲，但要注意它们所表达意思的语气的顺序是because, since, as, for；而且它们的具体用法还存在很大区别，我们千万不能混淆这四个词。

because表示“因为”，用来表示最直接的因果关系或是听话人所不知道的原因，它所表达的语气是这四个词中最为强烈的，它所引导的原因状语从句一般要放在主句之后。

还要注意两种情况也只能用because来回答：1. 用why来提问的特殊疑问句的回答，只能用because；2. 在强调句中，只能用because。

例：1. He didn’t attend the meeting because he had too much work to do.

2. It is because it rained last week that they put off the match.

since 在语气上仅次于because，更加强调“既然”，“由于”， 用来表示大家已然知道的事实。

例：Since we have no money, we can’t buy it.

as在语气上稍弱于since，不如since正式，而且经常用语口语。

例：As he wasn’t ready in time, we went without him.

for 是四个词当中表示“因为”，“由于”意思时语气最弱的一个， 它实际只是对它前面的主句加以补充说明理由或推断原因，要用分号和前面的主句分开。

例：I asked her to stay to tea, for I had something to tell her.

Exercise:

1. Why was he late for school? ____ he got up too late.

A. Because B. Since C. As D. For

2. “Is David at school today?” “No, he is at home ____ he has a bad cold.”

A. because B. since C. as D. for

3. It rained last night, ___ the ground is wet.

A. because B. since C. as D. for

4. ____ you haven’t free time, you needn’t go out with us.

A. Because B. Since C. As D. For

(key: AADB)