什么情况下只用whether不用if
1个回答

whether和if都可以引导宾语从句,表示“是否”,在口语或间接引语中两者可以互换使用.如: I wonder if / whether I can get some advice from you. Ask him whether / if he can come. 但在有些情况下,whether和if的用法有一定区别. 1. whether引导的从句常可以与连词or或or not直接连用,而if一般不能.如: 正: Let me know whether you can come or not. 误: Let me know if you can come or not. 2. 当宾语从句提到句首时,只能用whether引导,而不能用if.如: 正: Whether it is true or not, I can’t tell. 误: If it is true or not, I can’t tell. 3. whether可以引导带to的不定式,if则不能.如: 正: I don’t know whether to accept or refuse. 误: I don’t know if to accept or refuse. 4. whether及其引导的成分可放于介词之后,作介词的宾语,但if不能.如: 正: I worry about whether I hurt her feelings. 误: I worry about if I hurt her feelings. 5. whether可以引导从句,作主语、表语或同位语,而if不能.如: 正: It was uncertain whether he would come. 误: It was uncertain if he would come.