if与whether的区别.doc

在引导宾语从句时,whether 和if 通可以互换,在ask,care,doub,know,learn,msee,tell,try,wonder等动词之后尤其如此。例如:
I don’t know if/whether I can help you.
They don’t care a bit whether my reports are good or bad..
I wonder if you can examine him now.(高一册第十四页)
I am not sure if/whether I’ll have time.
但是,必须注意以下几点:
1)如果从句是否定结构,:
Well,think,and see if the most religious people aren’t those who fell that this life doesn’t gice them all they ,你想,那最虔诚的宗教徒,是不是就是那此觉得这现实的人生没有完全满足自己欲望的人?
Dinner was almost over when Dan,still looking hungry,grinned and asked Dave if he wasn’t going to have some (他看上去还没吃饱)笑着问戴维还要不要吃些面包。
I don’t care if he doesn’t show up .他来不来我都不在乎。
Let me know if you can’t meet me at Jackson and Throop Streets Wednesday afternoon at two o’,你是否能在杰逊街和思鲁街的黑心角来跟我相会。(<嘉莉妹妹>=
当然,对某些句子,人们可能会有不同的理解。如上面最后两列中的if 也可理解为引导条件状语从句:
他不来我也不在乎。
如果你在星期三下午二时不能和我在杰克逊街和思鲁街的黑心角相会,请通知我。
但是,当doubt是还定式时,则不用whether或if,要改用that,因为句子本身已没有“怀疑”或选择之意。度比较:
I don’t doubt that you are 。
She never doubt for a moment that she was 。
I doubt whether it’s true.
I doubt if that was what he wanted.
2)宾语从句前置时只能用whether,如:
Whether he lives there,I want to know.
Whether this is true or not ,I can’t say.
Whether we can relly help ypu ,I don’t know yet .我们是否真的能帮助你,我还不知道。
3)在decide,dicuss等动词后,通常只跟whether引导的宾语从句。如:
T