试一试，按下面的方法来记忆行不行：1.宾语从句由陈述句转变而来，连词用that(或省略）e.g. He is a good student. I know (that) he is a student.2.宾语从句由一般疑问句转变而来，连词用if/whether。e.g.
Is he a student?
I don't know if/whether he is a student.
Has he finished it?
I didn't tell her if/whether he had finished it.3.宾语从句由选择疑问句转变而来，连词用whether。e...
