由 whether,if 引导的宾语从句（一）由 whether,if 引导的宾语从句由 whether(if)引导的宾语从句，实际上是一般疑问句演变而来的意思是“是否” 宾语从句要用陈述句语序一般说来，在宾语从句中 whether 与 if 可以互换使用，但在特 殊情况下 if 与 whether 是不能互换的例句 ：I wonder whether(if) they will come to our party.（二）只 能用 whether，不能用 if 引导的宾语从句1. 在带 to 的不定式前：We decided whether to walk there.2. 在介词的后面：I’m thinking of whether we should go to see the film. 3. 直接与 or not 连用时例句：I can’t say whether or not thet can come on time.4. 当强调宾语从句并将其提前时只能用 whether如:Whether I'll have time to go with you I am not sure. 我很难说我 们是否有时间跟你们一起去。
5. 当 whether 和 or 连用表示明确的选择时如: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6. 动词 discuss，decide,consider，sure 等后习惯上也常用 Whether 引导从句， 不用 ifThey discussed whether they should leave at once. 他们讨论了是否应该马上离开We discussed whether the house should be sold. 我们讨论了这 房子是否应卖掉三）其他只能用 whether 不能用 if 的情况1.表语从句 用 whether 引导不用 if.如 : ① The doubt was whether you had broken the beautifulvase.疑问是你是否打坏了这只漂亮的花瓶2 同位语从句 用 whether 引导不用 if.如: The question whether we'll build another lecture building hasn't been settled.是否要另建一幢教学楼的问题还未决定。
3 位于句首的主语从句 只能用.whether如： Whether they win or lose is all the same to me. 他们是赢是输於我都一样.（此时 whether 不能换作 if ）It's doubtful whether there'll be any seats left. 有空座位了. (此句 whether 能换作 if)说不上还有没只能用 if 不能用 whether 引导的宾语从句1. if 引导条件状语 从句，意为“如果”例句：The students will go on a picnic if it is sunny.2. if 引导否定概念的宾语从句时例句：He asked if I didn’t come to school yesterday.3. 引导状语从句 even if（即使）和 as if （好象）时例句强化练习：：He talks as if he has known all about it.B1，We will go swimming ---------- it is fine tomorrow．A. while B. if C. when D. whetherA2. You have not yet answered my question _____ I can join in the party tonight or not.A. whether B. if C. that D. whichD3．— I d like to invite you to a party this evening.— Thank you, but _____ I’ll be free I m not sure at the moment.A. while B. if C. when D. whetherD4．---What are you anxious about?---___________A. If we succeed B.That we can succeed C. Do we succeed D.Whether we can succeedC5. Only when _____ the painting _____ decide ______the painting is worth buying.A. he sees, he can ,whether B. does he see, can he, ifC. he sees, can he ,whether D. sees he, he can,thatA6. _____ English is his favourite subjectA. I asked him if B. I asked him that whether thC. I asked him that D. I asked him which B7. _____ they’ll go to the Summer Palace ____ the weather.A. If; depends on B. Whether; depends upon C. Whether; depended on D. If; depended upon C8.It isn’t quite _____ ______ he will be present at the meeting.（it is 。
that 结构中只能有 certain 不能用 sure）A. sure; whether B. sure; if C. certain; whether D. certain; thatB9He asked me if I hadn't finished my homework．他问我是否没有完成作业A. while B. if C. when D. whetherB10. No one was sure _____ he would be asked to speak next year.A. when B. whether C. what D. howB11. I doubt _____ he will come here on time.。