if與whether用法區(qū)別3頁

1、 if與whether用法區(qū)別收集整理： 王俊堯1.下列情況只能用whether：（1）直接與or not連用時,往往用whether(ifor 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.) 讓我知道他是否能來。 I dont know whether or not he does any washing. (=I dont know whether / if he does any washing or not.)我不知道他在家洗不

2、洗衣服。I wonder whether we stay or whether we go.我想知道我們是去還是留。(2) 在介詞之后用whether。如：Im interested in whether he likes English我關(guān)心的是他是否喜歡英語。Were thinking about whether we can finish the work on time我們正在考慮是否能按時完成這項工作。I worry about whether I hurt her feelings我擔心是否傷了她的感情。()在不定式前用whether。如：He hasnt decided whet

3、her to visit the old man他尚未決定是否拜訪那位老人。I dont know whether to go我不知去否。He hasnt decided whether to go by bus or by train他還未決定是乘公共汽車去還是坐火車去。（）whether置于句首時，不能換用if。如：Whether this is true or not，I cant say這是否真的我說不上來。（）引導(dǎo)主語從句和表語從句時宜用whether。如： Whether she will come or not is still a question她是否能來還是個問題。 The

4、 question is whether we can catch the bus問題是我們能否趕上公共汽車。（）若用if會引起歧義時，則用whether。如：Please let me know if you like the book可理解為：aPlease let me know whether you like the book請告訴我你是否喜歡這本書。bIf you like the book，please let me know你如果喜歡這本書，請告訴我2. 如果賓語從句是否定式，就只能用if引導(dǎo)。如：dont care if it doesnt rain.我不管天是否不下雨。3.

5、 如果賓語從句原來是特殊疑問句，只需用原來的疑問詞引導(dǎo)。但一定要注意從句的語序是陳述語序，時態(tài)與主句相呼應(yīng)，句尾標點符號取決于主句。如果主句是問的就用“？”，是陳述的就用“”。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?你能告訴我我們今天下午將在哪兒開會嗎? ho bought the present for me？I dont knowI dont know who boug

6、ht the present for me. 我不知道誰給我買了禮物。當一個特殊疑問句本身就是陳述語序（即“主謂（賓）”或“主系表”結(jié)構(gòu)），將其變?yōu)殚g接引語（即賓語從句）時，無需改變語序。例如： Whats 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. 當主句的謂語動詞是think (認為), kno

7、w（知道）, believe（相信）, suppose（料想）, guess（猜想）等表示看法的詞時，有下列兩種情況：（1）如果主句的主語是第一人稱，后接的賓語從句的否定詞通常要移動到主句中，即否定主句動詞，這種形式稱為“否定的轉(zhuǎn)移”。這種前置否定的賓語從句要變成反意疑問句時，疑問部分的主、謂語要與從句一致。如：He isnt a student . I think. I dont think that he is a student, is he?She cant do that. We suppose. We dont suppose that she can do that, can s

8、he? (2)如果主句的主語是第二三人稱時，否定詞通常不轉(zhuǎn)移，但它的反意疑問句的主、謂語應(yīng)與主句一致。如：He thinks he cant go with you, does he?She thought she couldnt do that this afternoon, did she?6. 當主句的謂語動詞是think (認為), know（知道）, believe（相信）, suppose（料想）, guess（猜想）say（說）， imagine（想象）等表示看法的詞時（know除外），如果引導(dǎo)賓語從句的是特殊疑問詞，且是疑問句時，要將特殊疑問詞放到句首。即，特殊疑問詞+do y

9、ou thinksay/+ 從句如：(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作形式賓語的情況常用句型為：think/believe/find/feel + it + adj. / n. + that從句。如：I think it possible that he hasnt come.我認為他沒有來是可能的