名词性从句的主句在哪经常搞不明白句子中缺什么成分 哪个是主句 哪个是从句

For example:
Do you know whom they are looking for?你知道他们在找谁吗?（宾语从句,陈述语序.不能是whom are they looking for?）
I don’t know （who did it.）我不知道这是谁干的.（宾语从句.在从句中如果疑问词作主语,其陈述语序和疑问语序一致.）
She asked me where I had been.她问我到哪儿去了.（宾语从句.陈述语序,不能是where had I been.直接引语,间接引语.注意这句话的时态.）
主句Can you tell me( when the train will arrive?)-从句 你能告诉我火车什么时候到吗?(宾语从句.陈述语序,不能是when will the train arrive.直接引语,间接引语.)

有没有例题？