这个句子中的whether 为什么不能用if替换?there is still some doudt whether the meeting will be held in our school

这个句子中的whether 为什么不能用if替换?there is still some doudt whether the meeting will be held in our school 关于whether与ifI have no idea whether to visit my grandparents this Sunday.这句句子当中为什么只能用whether,不能用if?请详细回答```` 为什么只能用whether 引导主语从句为什么只能用whether,而不能用if呢?RT ___we will go camping tomorrow depends on the weather.为什么不能用if?只能用whether Please let me know whether or not you will come to the party.书上写这个句子里的whether or not不能用if代替 为甚麽 I asked her__if__ she was enjoying her dinner.为什么不能用whether这里的if为什么不能替换成whether? she stay at home.这个句子为什么不对为什么不能用stay,应用什么? She might have been exactly like that whether nothing had happened中为什么不能用whether而要用if? whether he woke or slept this subject is always in his mind为什么要whether or .不能用either or . Have decided（ ） on winter vacation?这个句子括号中为什么不能用what to do? I like taking photographs 为什么用taking不能用take 这个句子是现在进行式? 请问I went to the window to make sure whether something had happened.这个句子中的whether对不对? I went to the window to make sure whether something had happened.这个句子中的whether是不是错误的? I went to the window to make sure whether something had happened.这个句子中的whether是不是错误的? I don't know if he will come tomorrow.为什么要用if 不能用whether all people (whether)they are old oy young try their best...为什么不能用no matter which one is your mother?the woman with long black hair.为什么这个句子中的with不能改用has?这个回答句中,并没有含有be动词啊.为什么不能用has?英语高手们,求教求教