1、whether和ifwhether和if一、whether和if都可以用作连词,引导一个名词性从句,表示“是否”。whether可以引导主语从句、表语从句、宾语从句和同位语从句;而if只能引导宾语从句。 1引导宾语从句既可以用whether,也可以用if,两者常可以互换。whether从正反两个方面提出疑问,选择意义较强,多用于正式文体中;而if多用于口语,比较强调单方面,如: He asked me whether / if I could lend him my bike. Could you tell us whether / if it snows in winter in Austr
2、alia? I want to know whether / if you can come or not. She asked them whether / if they had gone there by car or by train. 值得注意的是: whether 和if都可以和or not连用,但是whether之后可以直接跟or not,而if则不能,如: I dont care whether or not your car breaks down. I dont know whether or not hes coming. 但是不可以说: I dont care if o
3、r not your car breaks down. 在个别动词之后,如discuss 等,只跟用whether引导的宾语从句,如: They discussed whether they should close the shop. We discussed whether Mary could join us. whether 可以引导从句作介词的宾语,而if则不能,如: Im not interested in whether theyll go or not. It depends on whether we have got enough money. whether可以直接跟动词
4、不定式连用,而if则不能,如: I didnt know whether to laugh or to cry. She hasnt decided whether to go or not. He was wondering whether to go home or stay at school. 2引导主语从句(包括从句在句首的位置)应当用whether,不用if,如: Whether it is true remains a problem. Whether he can stay with us is another matter. Whether he will come, I a
5、m not sure. Whether or not he did it, I cannot tell. 3引导表语从句用whether,不用if,如: The question is whether you should accept it. The question is whether he will speak at the meeting. 4引导同位语从句用whether,不用if,如: The question whether hell attend the meeting is essential. I am in doubt whether I should agree to
6、 the plan. 二、whether 还可以引导让步状语从句,意为“不管;无论”;而if则不能引导这种从句,如: I shall tell her about it whether you agree or not. Whether or not the figures are accurate, we have to recheck them. Whether or not we had a baby, we could not survive just on my salary. 三、if还可以引导条件状语从句,意为“如果;假如”,而whether则不能引导这种从句,如: We sha
7、ll do this experiment if we have time. 四、如果在从句中使用if表示“是否”容易与表示条件的状语从句混淆时,应注意避免使用if,例如:Please let us know if they are coming. 这句话可以理解为“如果他们要来,请通知我们一下。”也可以理解为“请告诉我们,他们是否要来。”若表示后一层意思,应当使用,以免引起误会。他人总结2:一、引导宾语从句,一般既可用whether也可用if。但 1 or not放在whether之后时,只能用whether不用if。 I dont know whether or not he will c
8、ome. 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 dont know whether/if he will come or not.我不知道他是不是回来。 2 在强调任意选择时,用whetheror,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。 注:whether和or一起还有“不管”之意,引导让步状语从句。 Whether he drives or takes the train
9、, he will be here on time.不管开车来还是乘火车来,他都会准时到。 3 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。 4 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。 5 作discuss,decide等动词的宾语时,用whether不用if。 We discussed whether we should close the shop.我们讨
10、论是不是该关掉商店。 6 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 Id 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。 7 容易产生歧义时用whether不用if来表示“是否”。 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。 8 如果宾语从句为否定句时,则只用if不用
11、whether。 I dont know if it wont rain tomorrow.我不知道明天是不是会下雨。 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。如: Whether it is true remains a question.(主语从句)那是不是真的还是个问题。 The question is whether it is true.(表语从句)问题是是不是真的。 We have a doubt whether it is true.(同位语从句) 我们怀疑那是不是真的。 注:whether引导主语从句放在主句之后时可用if来代替。 It is u
12、nclear whether/if he likes the present.他是不是喜欢那个礼物还不清楚。 三、用在动词不定式之前时用whether不用if。 I dont know whether to go there at once. 我不知道是不是该立刻去那里。 四、注意 1if除了引导上述从句还可以引导条件状语从句,是假如;如果之意,此时就不用再遵循上述种种法则。 If you ask him, he will help you 2whether可以引导让步状语从句,是不管;无论 之意。(此时常用whetheror)如: I shall go, whether you come with me or stay at home
copyright@ 2008-2022 冰豆网网站版权所有
经营许可证编号:鄂ICP备2022015515号-1