who are you waiting for同义句

who are you waiting for同义句
=【For whom 】are you waiting?Whom是什么……whom 是who 的 宾格，作介词 for 的宾语。who 可以作主语，也可以作宾语，但是如果前面有介词时，只能用 whom。原句 who are you waiting for？也可以改为 Whom are you waiting for?当 for 放在句首时，只能说：For whom are you waiting ?你在等谁？