There is somebody knoking at the door.Go to see________.为什么填who it is?为什么不填whom it is或who is it,请对这几种解释分别进行分析

翻译：There is somebody,there isnobody! There is no message that from somebody 如何翻译 Is there ___in the room?No,there is __in it .A somebody:nobodyB anybody:somebodyC somebody:anybodyD anybody:nobody Is there anybody in the classroom?还是Is there somebody in the classroom? Somebody Out There 歌词 阐述：is there no one else?is there no one else?is there anybody else?is there anybody?is there somebody? where is bob?there is somebody here___wants to speak to him There is somebody knocking at the door .Go to see( ) it is. miss somebody is very how is somebody hear!somebody is crying everybody is somebody是什么意思 Is there here A anybody B somebody C everybody D nobody If there is somebody i need to love ,that must be Is there ( )here Yes I'm upstairs Please come and help meanybody 还是somebody There is__(nobody,somebody.anybody,everybody)knocking at the door,Go and see who it is is there something wrong?Years go by,will still be waiting for somebody else to understand? There is somebody here who wants to speak to you中