第1个回答 2007-05-12
相同点:if和whether都可意为是否,用于宾语从句中.
不同点:1.当宾语从句中有or not时,则只能用if,不能用whether.
I don't know whether he will come or not.(对)
I don't know if he will come or not.(错)
我不知道他是否会来.
2.if除了可以用于宾语从句中意为是否,还可以用于条件状语从句中意
为如果,而whether则没有此用法.
I will go if it doesn't rain tomorrow.
如果明天不下雨我就去.
第2个回答 2007-05-12
if, whether在作是否解时引导宾语从句常放在动词know, ask, care, wonder, find out 等之后.
但少数动词如leave, put, discuss, doubt后的宾语从句,常用whether引导.
e.g.: I put it to you whether we should start earlier.
e.g.: I doubt whether they'll keep their word.
whether后可加or not,if 不可以.
I don't care whether the work will take long or not.
I wonder whether or not we should make it clear that we've lost this game.
在不定式前,只用whether.
i am just wondering whether to stay for another hour or just start off right away.