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：\x0dI wonder if / whether I can get some advice from you.\x0dAsk him whether / if he can come.\x0d但在有些情况下,whether和if的用法有一定区别.\x0d1.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：\x0d正：Let me know whether you can come or not.\x0d误：Let me know if you can come or not.\x0d2.当宾语从句提到句首时,只能用whether引导,而不能用if.如：\x0d正：Whether it is true or not,I can’t tell.\x0d误：If it is true or not,I can’t tell.\x0d3.whether可以引导带to的不定式,if则不能.如：\x0d正：I don’t know whether to accept or refuse.\x0d误：I don’t know if to accept or refuse.\x0d4.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：\x0d正：I worry about whether I hurt her feelings.\x0d误：I worry about if I hurt her feelings.\x0d5.whether可以引导从句,作主语、表语或同位语,而if不能.如：\x0d正：It was uncertain whether he would come.\x0d误：It was uncertain if he would come.\x0d正：His first question was whether Tom had arrived yet.\x0d误：His first question was if Tom had arrived yet.