if釋義

conj. 即使; 如果，倘若; 〈口〉是否; 假設(shè);

n. 條件，設(shè)想;

if的用法

if從句一般有三種用法

1、主將從現(xiàn) （主句為一般將來時,從句為一般現(xiàn)在時）；

eg:If it rains(從句) ,I will stay at home（主句）.

=I will stay at home if it rains.

2、主句含有情態(tài)動詞 （must、may、can etc.）從句為一般現(xiàn)在時；

eg:If you drive too fast ,you may have an accident.

=You may have an accident if you drive too fast

3、主句為祈使句,從句要用一般現(xiàn)在時態(tài)；

eg:Don't play computer games if you don't finish your homework.

備注：

1、If 于句首時中間用逗號隔開,主句后不用逗號.

2、if 可用unless(除非...) 替換.unless= if...not...

3、注意虛擬語氣 主句和從句都為一般過去式

eg:If I was a bird ,I could fly.（事實我不可能是鳥）

if相關(guān)詞組

if you want/like 如果你愿意的話

You can come and stay with us if you want.

if so如果是的話

Are you planning to return to work, and if so, who is going to look after the baby?

if not如果不是的話

Has anyone dealt with the technical problems? And if not, why not?

if necessary/if possible 如果必要/可能的話

We are ready to fight for our rights if necessary.

I should like to be back here by 10:30 if possible.

even if即使

I’d rather never sell this painting, even if they offered me a million dollars.

what if 要是……，那怎么辦？ 如果……那會怎樣？

What if the boss walked in here now and saw us?

as if好像是……

She always talks to me as if she was my sister.

if的用法例句

1、She gets very upset if I exclude her from anything

要是有什么事情我不讓她參加，她會非常難過。

2、He asked if I had left with you, and I said no

他問我是否和你一塊兒離開的，我說不是。

3、Sometimes, that standard is quite difficult, if not impossible, to achieve

有時即便有可能達到那個標準，那也是非常困難。

4、If I could just make another small point about the weightlifters in the Olympics

請允許我就有關(guān)奧運會舉重運動員的問題再補充一點。

5、I wonder if you'd be kind enough to give us some information, please?

請問您能不能給我們提供一些信息？