高中語法專練：ii. as作連詞引導(dǎo)原因狀語從句，與because的區(qū)別

ii. as作連詞引導(dǎo)原因狀語從句，與because的區(qū)別

1. 一般說來，as表示聽者已經(jīng)知道的原因，因而常常位于句首；而because表示聽者未知的原因，因而常常位于句尾，成為信息的焦點(diǎn)。

I don't want it because it is too long .

我不想要它，因?yàn)樗L(zhǎng)了。

As I am leaving tomorrow, I've bought you a present.

因?yàn)槊魈煳乙?，我給你買了件禮物。

As all the seats were full, we had to stand on the bus.

由于座位全滿了，我們只好在公共汽車上站著。

It was easy for me to guess what he was going to do as he was my close friend.

我很容易猜出來他要干什么，因?yàn)樗俏业暮门笥选?

2. as從句不能回答why提出的問題，而because從句可以回答why提出的問題。

—Why shouldn't I come?

—Because you're too busy.

——為什么我不應(yīng)該來？

——因?yàn)槟闾α恕?

3. as從句不能在強(qiáng)調(diào)句型中作為被強(qiáng)調(diào)的部分，而because從句能在強(qiáng)調(diào)句型中成為被強(qiáng)調(diào)的部分。

It was because he was ill that he missed yesterday's class.

正是因?yàn)樯×耍耪`了昨天的課程。

專項(xiàng)練習(xí)

1. _______ I am ill, I can't go.

A. As

B. Since

C. Because

D. For

2. She lied to us _______ she had to do in order to get a job.

A. as

B. since

C. because

D. for

3. _______ the weather was fine, we decided to walk to the restaurant.

A. As

B. Since

C. because

D. For

4. It was _______ he missed the bus that he came late.

A. as

B. because

C. for

D. since

5. —Why did you change your mind?

—_______ I found the plan was unreasonable.

A. As

B. For

C. Since

D. Because

答案速查　1-5　ACABD