在4种名词性从句里,if只能引导宾语从句,不能引导主语从句补语从句和同位语从句。as if可以引导补语从句。在主语从句里,是。。。还是。。。用whether来引导。
whether he is nice or not remains to be seen.
it's uncertain whether he will come here or not.
whether we are going to visit the Great wall or not hasn't been decided.
if 可以引导主语从句,如果不可以,请说明原因。谢谢。