whether, if用法區別總結
在名詞性從句中常出現連詞whether和if,使用時兩詞還常可替換,但有時也不能替換。下面是小編整理的一些關於whether, if用法區別， 希望對大家有幫助。
whether, if 用法區別總結
一、在引導賓語從句時，應注意：
1、表示“是否”時，兩詞都能引導賓語從句。
①I don't know whether/if I will be able to come.我不知道我是否能來.
②She asked me whether/if I was interested in working for her.她問我是否有興趣爲她工作。
③We'll be told tomorrow whether we should take the exam or not.我們明天才知道是不是應該參加考試.
④I asked him whether he had done all the work himself or whether he had had any assistance. 我問他這些工作都是他自己做的還是別人幫他做的.
⑤I wonder if/whether you can examine him now.
( 注意: 在兩個供選擇的從句之間若用or字, 則須重複whether一字. )
注: ⑴當強調賓語從句並將其提前時只能用whether。
如:Whether I'll have time to go with you I am not sure.我很難說我們是否有時間跟你們一起去。
二、whether和if都可以與or not連用; 但whether和or not寫在一起時，或在動詞短語後，只能用whether，不能用if。如：
I don't care whether (或if) it will rain or not.
I don't care whether or not it will rain. (不用if)
I don't care about whether or not it will rain. (不用if)
2、賓語從句移置句首時，用whether，不用if。
Whether it is true or not， I can't say.
=I can't say whether/if it is true or not
3、賓語從句爲否定形式時，通常用if，而不用whether。
I asked Tom if Mary wouldn’t come.
4、動詞discuss，decide, consider等後習慣上也常用Whether引導從句，不用if。
They discussed whether they should leave at once.他們討論了是否應該馬上離開。
We discussed whether the house should be sold. 我們討論了這房子是否應賣掉。?
We discussed whether we should buy the gift for him.
三、在下列情況下，只能用whether，不能用if。
1、與不定式連用時，只能用whether.
He can't decide whether to accept or refuse.
2、在介詞後，只能用whether。
Everything depends on whether he is ready.
I don't care about whether or not it will rain.
3、在名詞後作同位語時，只能用whether。
The question whether they ought to stop working was discussed among the workers.
I have no idea whether he is there.
4、引導主語從句時，只能用whether。
Whether he comes or not doesn't concern me.
5、引導表語從句時，只能用whether。
What Maria doesn't know is whether there will be enough snow.
6、當whether和or not連用時，只用whether不用if。如:
I don’t know whether or not he will come.我不知道他是不是回來。
I'll be happy whether/if I get the job or not我能不能得到那份工作都一樣高興。注意：當or not放在whether引導的從句句尾，則可以用if來替換。
7、 當whether和or 連用表示明確的選擇時，只用whether不用if。
He asked me whether I wanted to go there by train or by bus.他問我是想乘火車還是坐公共汽車去那裏。
He hesitated about whether he should drive or take the train.他開車去還是坐火車去, 猶豫不決
注:whether 和or 連用還可以引導讓步狀語從句,此時也不用if。如：We'll go on with the work, whether we can find the necessary tools or not.
不管我們能否找到所需的工具,我們要把這件工作做下去。
Whether or not it rains / Whether it rains or not, we're playing football on Saturday.無論下不下雨, 我們星期六一定踢足球.
8、在動詞不定式之前，只能用whether，不能用if。
①The question is whether to go to Munich or Vienna.問題是去慕尼黑還是去維也納.
②She doesn't know whether to get married now or wait.是否現在結婚或是等待她不知道。
③We were wondering whether to go today or tomorrow.我們弄不清是今天走還是明天走.
④I'm not sure whether to resign or stay on.我拿不準主意是辭職還是留任.
四、if可引導條件狀語從句，譯作“如果”，whether可引導讓步狀語從句，譯作“不管、無論”。
If I were you，I would not buy.
Whether he agrees or not，I shall go there.
We'll go on with the work, whether we can find the necessary tools or not.不管我們能否找到所需的工具,我們要把這件工作做下去。
Whether or not it rains / Whether it rains or not, we're playing football on Saturday.無論下不下雨, 我們星期六一定踢足球.
五、whether和if均可用來引導主語從句，但if引導的從句不能位於句首。
Whether they win or lose is all the same to me. 他們是贏是輸於我都一樣.(此時whether不能換作if )
It's doubtful whether there'll be any seats left.說不上還有沒有空座位了. (此句whether能換作if)
六、表語從句、同位語從句用whether引導不用if.
The doubt was whether you had broken the beautiful vase.疑問是你是否打壞了這隻漂亮的花瓶。
The question whether we'll build another lecture building hasn't been settled.是否要另建一幢教學樓的問題還未決定。
