1、1.whether和if均可用來引導主語從句，但if引導的從句不能位于句首。如： 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 ） Its doubtful whether therell be any seats left. 說不上還有沒有空座位了. (此句whether能換作if) 2.whether和if均可用來引導賓語從句。如：I dont know whether/if I will be able to come.我不知道我是否能來. She asked me whether

2、/if I was interested in working for her.她問我是否有興趣為她工作。Well 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. I 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. ( 注意: 在兩個供選擇的從句之間若用or字, 則須重復whether一字. ) 注: 當強調賓語從句并將

3、其提前時只能用whether。 如:Whether Ill 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。 從句作介詞賓語時只用whether不用if。如:She was undecided about whether she should accept his offer.她拿不定主意應該不應該接受他的好意 當whether和or not連用時，只用whether不用if。當or not放在whether引導的從句句尾，則可以 用if來替換。 如: I dont know whether or not he will com

4、e.我不知道他是不是回來。 Ill 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 當whether和or 連用表示明確的選擇時，只用whether不用if。 如: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里。 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

5、時也不用if。 如：Well 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, were playing football on Saturday. 無論下不下雨, 我們星期六一定踢足球. 動詞discuss，decide,consider等后習慣上也常用Whether引導從句，不用if。 They discussed whether they shoul

6、d 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。3.表語從句用whether引導不用if. 如:The doubt was whether you had broken the beautiful vase. 疑問是你是否打壞了這只漂亮的花瓶。4. 同位語從句用whether引導不用if. 如:The question whether well build another lecture building hasnt been settled. 是否要另建一幢

7、教學樓的問題還未決定。5. 在動詞不定式之前，只能用whether，不能用if。如:The question is whether to go to Munich or Vienna. 問題是去慕尼黑還是去維也納. She doesnt knows whether to get married now or wait. 是否現在結婚或是等待她不知道。 We were wondering whether to go today or tomorrow. 我們弄不清是今天走還是明天走. Im not sure whether to resign or stay on. 我拿不準主意是辭職還是留任.

8、強化練習： 1. The question has not been answered _ Taiwan will be included on the Olympic torch relay route.Athat Bwhether Cwhich Dif2. You have not yet answered my question _ I can join in the party tonight or not. A. whether B. if C. that D. which3 I d like to invite you to a party this evening. Thank

9、you, but _ Ill be free I m not sure at the moment. A. while B. if C. when D. whether 4-What are you anxious about? -_A. If we succeed B.That we can succeed C. Do we succeed D.Whether we can succeed5. Only when _ the painting _ decide _the painting is worth buying. A. he sees, he can ,whether B. does

10、 he see, can he, ifC. he sees, can he ,whether D. sees he, he can,that6. _ English is his favourite subject A. I asked him if B. I asked him that whether C. I asked him that D. I asked him which7. _ theyll go to the Summer Palace _ the weather. A. If; depends on B. Whether; depends upon C. Whether;

11、depended on D. If; depended upon8.It isnt quite _ _ he will be present at the meeting. A. sure; whether B. sure; if C. certain; whether D. certain; that9. _ the 2008 Olympic will be held in Beijing is not known yet. A. Whether B. If C. Whenever D. That10. No one was sure _ he would be asked to speak

12、 next year. A. when B. whether C. what D. how11. It is still a question to us all _ there is any living thing in some other places in the space. A. whether B. which C. what D. where12. I doubt _ he will come here on time.A. that B. whether C. when D. where13. The point is not who said the words, _ they are true or not.A. but whether B. and whether C. but how D. and how14. “What did he ask you?” “_ I would be late.”A. That B. When C. Where D. Whether15. He treated all the people around him,_he knew or he didnt know,_. A. if, friend