总结if与whether用法区别.doc
if与whether用法区别
收集整理:王俊尧
1.下列情况只能用whether:
(1)直接与or not连用时,往往用whether(if…or not也可以使用)。如: Let me know whether or not he will come.
(= Let me know whether / if he will come or not.)
让我知道他是否能来。
I don't know whether or not he does any washing.
(= I don't know whether / if he does any washing or not.)
我不知道他在家洗不洗衣服。
I wonder whether we stay or whether we go.
我想知道我们是去还是留。
(2) 在介词之后用whether。如:
I'm interested in whether he likes English.
我关心的是他是否喜欢英语。
We're thinking about whether we can finish the work on time.
我们正在考虑是否能按时完成这项工作。
I worry about whether I hurt her feelings.
我担心是否伤了她的感情。
(3)在不定式前用whether。如:
He hasn't decided whether to visit the old man.
他尚未决定是否拜访那位老人。
I don't know whether to go.我不知去否。
He hasn't decided whether to go by bus or by train.
他还未决定是乘公共汽车去还是坐火车去。
(4)whether置于句首时,不能换用if。如:
Whether this is true or not,I can't say.
这是否真的我说不上来。
(5)引导主语从句和表语从句时宜用whether。如:
Whether she will come or not is still a question.
她是否能来还是个问题。
The question is whether we can catch the bus.
问题是我们能否赶上公共汽车。
(6)若用if会引起歧义时,则用whether。如:
Please let me know if you like the book.可理解为:
a.Please let me know whether you like the book.
请告诉我你是否喜欢这本书。
b.If you like the book,please let me know.
你如果喜欢这本书,请告诉我
2. 如果宾语从句是否定式,就只能用if引导。如:
Idon’t care if it doesn’t rain.
我不管天是否不下雨。
3. 如果宾语从句原来是特殊疑问句,只需用原来的疑问词引导。但一定要注意从句的语序是陈述语序,时态与主句相呼应,句尾标点符号取决于主句。如果主句是问的就用“?”,是陈述的就用“.”。如:
Where will we have the meeting this afternoon? Could you tell me? →
Could you tell me where we will have the meeting this afternoon?
你能告诉我我们今天下午将在哪儿开会吗?
Who bought the present for me?I don't know.→
I don't know who bought the present for me.
我不知道谁给我买了礼物。
4.当一个特殊疑问句本身就是陈述语序(即“主+谓+(宾)”或“主+系+表”结构),将其变为间接引语(即宾语从句)时,无需改变语序。例如:
What’s the matter with him? She asked me. →
She asked me what was the matter with him.
Who looks after your grandfather? He asked me. →
He asked me who looked after my grandfather.
5. 当主句的谓语动词是think (认为), know(知道), believe(相信), suppose(料想), guess(猜想)等表示看法的词时,有下列两种情况:
(1)如果主句的主语是第一人称,后接的宾语从句的否定词通常要移动到主句中,即否定主句动词,这种形式称为“否定的转移”。这种前置否定的宾语从句要变成反意疑问句时,疑问部分的主、谓语要与从句一致。如:
He isn’t a student . I think. →
I don’t think that he is a student, is he?
She can’t do that. We suppose. →
We don’t suppose that she can do that, can she?
(2)如果主句的主语是第二三人称时,否定词通常不转移,但它的反意疑问句的主、谓语应与主句一致。如:
He thinks he can’t go with you, does he?
She thought she couldn’t do that this afternoon, did she?
6. 当主句的谓语动词是think (认为), know(知道), believe(相信), suppose (料想), guess(猜想)say(说), imagine(想象)等表示看法的词时(know除外),如果引导宾语从句的是特殊疑问词,且是疑问句时,要将特殊疑问词放到句首。即,特殊疑问词+do you think/say/…+ 从句.如:
(1) Do you say how old he is? (×)
How old do you say he is? (√)
(2) Do you think what is the fastest way to travel ? (×)
What do you think is the fastest way to travel ? (√)
(3) Do you suppose what he wanted? (×)
What do you suppose he wanted? (√)
7. it作形式宾语的情况
常用句型为:think/believe/find/feel + it + adj. / n. + that从句。如:
I think it possible that he hasn’t come.
我认为他没有来是可能的。
I feel it easy that he studies English well.
我发现他学习英语是容易的。
I feel it your duty that you serve the people.
我觉得为人民服务是你的职责。
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