Whether和if的用法比较

Whether 和 if 都可以做“是否”解,但二者在具体使用时有一定的区别。

一般情况下,if 和 whether 均可引导动词后的宾语从句,常可以互换,如:

He asked me whether /if we wanted a drink.

I don’t know whether/if I can help you.

He didn’t know whether/if she was a nurse

I wonder whether/if you can examine him now.

They don’t care a bit whether/if my reports are good or bad..

但在decide,discuss后用whether不用if。如:

The committee are discussing whether he can join the Party.

The old lady has not decided whether she will live with her daughter in the countryside.

当使用 if 会引起歧义时应用 whether, 如:

Please let me know whether you want to go.(如换成if则既可看成条件从句又可看做宾语从句)

宾语从句前置时只能用 whether, 如:

Whether he lives there,I want to know.

Whether this is true or not ,I can’t say.

Whether we can relly help you ,I don’t know yet .我们是否真的能帮助你,我还不知道。

另外,whether 引导的从句的谓语动词不能用否定形式,但 if 引导的从句的谓语可以用否定形式,如:

I don’t care whether it doesn’t rain.(错)

I don’t care if it doesn’t rain.(正确)

介词后只能用 whether,不能用 if ,如:

I’m interested in whether you’ve finished the work.

There was a big argument about whether we should move to a new house.关于我们是否应搬新家发生了激烈的争论。

It depends on whether the letter arrives in time.这取决于信是否来得及时。

在带 to 的不定式前只能用whether,不能用 if,如:

I can’t decide whether to get marrried now or wait.我不能决定是该现在就结婚还是等待。

She hasn’t decided whether to go or not.她还没决定去还是不去。

在引导主语从句,表语从句和同位语从句时,一般只能用wheher 不用if,如:

Whether he’ll attend the meeting is unknown.

Whether they win or lose is all the same to me.

Whether it will do us harm or good remains to be seen.

但是,当采用形式主语it,而将主语从句后置时,用whether 和 if均可(尽管 whether 更常用):

It makes no difference to me whether/if it’s foggy or clear.

It’s not clear to me whether/if she likes the present.

The question is whether the man can be trusted.

The question is whether they can cooperate with us.问题是他们能否与我们合作。

The question whether he should come himself or send a substitute must be decided upon.他该亲自来还是派人替他来,这个问题必须定下来。

We will soon discuss the problem whether we should take some effective measures to protect the animals and plants in our region.我们很快将讨论是否应该采取一些有效措施来保护本地区的动植物这一问题。

Have you discussed the question whether you have enough time to do the work?你们有没有讨论过是否有足够的时间来做这项工作?

当用 or 提出两种选择时,whether 更常用,尤其是在正式文体中,如:

I don’t know whether I should go away or stay here.

Whether they do it or not matters little to us.他们干还是不干,与我们关系都不大。

What I want to know is whether the professor will come here or not next week.我想知道的是教授下周还来不来。

The little girl asked her father whether she should go to the party or not .女孩问父亲她应不应该参加这个晚会。

I don’t know whether it is raining or not .

但是,随着语言的发展,if 与 or,or not 也已为人们所接受,例如:

He didn’t know whether /if we should write or phone.(《最新牛津现代高级英汉汉英双解词典》)

How can you tell if the charge is positive or negative?你怎么知道电荷是正的还是负的?(《英汉技术词典》)

I wonder if /whether he is at home (or not ).(Harold E.Palmer:A Grammar of English Words)

I don’t care if/whether you car breaks down or not .(Geoffrey Jan Svartvik:A Communicative Grammar of English )

Let me know whether/if you can come or not .(Michael Swan: Practical English Usage)

然而,直接与 or not 连用时,则只能用 whether ,换句话说,只有 whether or not ,没有 if or not,如:Let me know whether or not you can come.告诉我你来还是不来。I wonder whether it is or not big enough.我不知道它是否够大。

以上是 if 和whether表示“是否”之意时的用法区别。此外,if 还有“假如”之意,引起条件状语从句;而 whether 另有“不管,无论”之意,引起让步状语从句。如:

If you want to learn a muscial instrument, you have to practice.如果你想学习一种乐器,你得练习它。You may leave the table if you have finished eating.你要是吃饱了,就可以离席了。

Whether it rains or not,we’ll go camping.无论下不下雨,我们都要去野营。

总之,尽管 if 和 whether 在不少的情况下可通用,但二者的区别也是显而易见的,在使用中需要严格加以辨析。