if 的用法

D her the answer if she ____me. 5． I ____
A. can tell, will ask B. will tell, will ask C. would tell, ask D. will tell, asks 6. – What are you going to do tomorrow? --We’ll go to the library tomorrow if it ___. D A. isn’t rain B. rain C. won’t rain D. doesn’t rain 7.—Do you know when he will come back tomorrow? A --Sorry, I don’t know. When he ____ back, I’ll tell you. A. comes B. will come C. come D. may come 8. What will you do if you _____ to the old folk’s home A visit? A. go B. went C. going D. will go
if 的用法
嬉子湖中心学校
903
一、if 作为连词，引导条件状语从句，它表示 的意思是“假如”“如果”等。在复合句中如 果主句用将来时，则if引导的状语 从句用一般现在时 1. If it doesn’t rain, we will go to the park next Sunday. 二、if还可以引导让步状语从句。这时if当作 “即使是”，“虽说”解
五、if后接否定动词，用于感叹句中，表示沮丧、 惊奇等。
I. Well，if I haven’t left my false teeth at home! 真倒霉，我把假牙丢在家里了! 2. And if he didn’t try to knock me down!(What do you think he did! He tried knock me down!) 你猜他想做什么?他想把我撞倒! 六、用于虚拟语气中，if从句中用过去式，表示 不可能实现，大概不会实现或提出作为考虑的假 定条件 1. If you were a bird, you could fly.假使你 是只鸟，你便会飞了。
9. If I eat ____ food, I’ll be very fat. C A. too many B. many too C. too much D. much too 10. I’ll give the book to him if heB here next Sunday. ___ A. will come B. comes C. is coming D. came 11. There ____an English film in our school tomorrow. C A. is going to have B. will have C. is going to be D. has 12. Could you tell us where ____？ B A. will the next Olympic Games held B. the next Olympic Games will be held C. would the next Olympic Games be held D. the next Olympic Games would be held C 13. When my mother returned last night, I ____ a book. A. read B. am reading C. was reading D. am going to read
否”。 Please let me know if you need help. 如果你需要帮 助请告诉我。或：请告诉我你是否需要帮助。对 比：Please let me know if you need help.请告诉我 你是否需要帮助。
H 如果宾语从句为否定句时，则只用if不用
whether。 I don’t know if it won't rain tomorrow. 我不知道明天是不是会下雨。
D 从句作介词宾语时只用whether不用if。
It depends on whether it will be fine.那 得看是不是晴天。
E 作discuss等动词的宾语时，用whether不
用if。 We discussed whether we should close the shop. 我们讨论是不是该关掉商店。
B 在强调任意选择时,用whether…or,此时不用if
替换whether。 He asked me whether I wanted to go there by train or by bus. 他问我是想乘火车还是坐公共汽车去那里。
C 虽引导宾语从句，但为了强调宾语部分，也
可把从句放在句首，此时只用whether不用if。 Whether he will come I am not sure. 他是不是来我拿不准。
1. If you _____ to the party, you’ll have a great C time. A. will go B. went C. go D. going D 2. It will be a long time ____ Peter _____ his work. A. since, has finished B. after, finishes C. when, will finish D. before, finishes. B 3. What will father _____ us from Japan? A. take B. bring C. carry D. make A 4. Weifang is famous ______ kites A. for B. to C. on D. with
1. If she’s poor，at least she’s honest． 虽说她很穷，但至少她还是诚实的。 2. If I am wrong，you are wrong， too． 即使说 我错了，那么你也不对。
三、if作为连词还可以引导宾语从句。引导宾 语 从句时和whether意思相同。 1. Lily asked if ／ whether she liked it. 莉莉问她是否喜欢它。 四、if引导时间状语从句，当if做“当”或 “无论何时”解而不含有条件之义时，if从句 中的时态与主句中的时态相同。 1. If you mix yellow and blue，you get green． 你将黄色与蓝色混合，便会得到绿色。 2. If she wants the servant，she rings the bell. 每当她需要仆人时，她便按铃。
5. Only when _____ the painting _____ decide ______the C painting is worth buying. A. he sees, he can ,whether B. does he see, can he, if C. he sees, can he ,whether D. sees he, he can,that 6. _____ English is his favourite subject A A. I asked him if B. I asked him that whether C. I asked him that D. I asked him which 7. _____ they’ll go to the Summer Palace ____ the B weather. A. If; depends on B. Whether; depends upon C. Whether; depended on D. If; depended upon 8.It isn’t quite _____ ______ he will be present at the C meeting. A. sure; whether B. sure; if C. certain; whether D. certain; that
（二）在引导主语从句、表语从句、同位语从句 时一般用whether不用if。 ⑴Whether it is true remains a question. (主语从句)那是不是真的还是个问题。 ⑵The question is whether it is true. (表语从句)问题是是不是真的。 ⑶We have a doubt whether it is true. (同位语从句) 我们怀疑那是不是真的。
（三）用在动词不定式之前时用whether不用if。
I don’t know whether to go there at once. 我不知道是不是该立刻去那里。
Fra Baidu bibliotek
1. The question has not been answered ____ B Taiwan will be included on the Olympic torch relay route. A.that B.whether C.which D.if A 2. You have not yet answered my question _____ I can join in the party tonight or not. A. whether B. if C. that D. which 3．— I d like to invite you to a party this evening. — Thank you, but _____ I’ll be free I m D not sure at the moment. A. while B. if C. when D. whether D 4．---What are you anxious about? ---_________ A. If we succeed B.That we can succeed C. Do we succeed D.Whether we can succeed
A or not放在whether之后时，只能用whether不
用if。 I don’t know whether or not he will come. 我不知道他是不是回来。 注1：如果or not放在whether所引导的从句句尾， 则可以用if来替换。 I don’t know whether/if he will come or not. 我不知道他是不是回来。
七、if与其它一些介词的连用。
首先，as与if连用，它的意思是：“仿佛、好像” 同样引导从句。 1. It isn’t as if we are rich．(We are not rich． 我们不像富有的样子。(即我们不富有) 2. It isn’t as if he doesn’t know the ruler．(i．e．He does know the rulers．) 他不像不懂规则的样子。(即他懂得规则) 另外as if还可以引导感叹句。
As if I would allow it!(i.e．I would certainly not
allow it!)好像我会答应似的!(我才不会答应哩!)
其次, if与only连用。常表示愿望或一个未实现的 条件，尤其用于感叹句中。 1. If only he arrives in time! 他若能及时到达就好了! 2. If only she would marry me! 但愿她能嫁给我！ 3. If only she had known about it!（But she didn’t know.） 她那时要是知道（但她不知道）这事就好了! 八、Whether 和 if的用法区别 （一）引导宾语从句，一般既可用whether也可 用if。但
F 句子中有if引导的条件句，如再有表示“是否”
的宾语从句，用whether不用if。
He asked me whether I’d move to New York if I got the job. 他问我如果我得到那份工作是否会搬家到纽约。
G 容易产生歧义时用whether不用if来表示“是
另外，if从句中用过去完成式，表示过去未实现
的条件(例如由于不可能实现或某人之未能实行)。 1. If they had started earlier，they would have arrived in time． 要是他们早些动身，他们便可及时到达了。 第三，在文学体裁中，if有时可省略，然后将主 语与所用的限定动词(尤其是were，had，should) 倒置。 1. Should it (=if it should)be necessary，I will go. 倘若有必要，我会去的。 2. Were I(=if I were) in your place，I would do the same. 如果我处于你的位置，我也会这样干的。