合并宾语从句时,若从句为一般疑问句,什么时候用if,什么时候用whether?

下面两种情况用whehter,不用if
1.作介词的宾语时,如：
He was worried about whether he passed the English examination.
2.句子中有or not 时.如：
It doesn't matter whether she will come or not.