是谁呀who is it?为什么用it不用she或he?

是谁呀who is it?为什么用it不用she或he? who is it 它是谁 请教高人英语：当有人敲门,你不知道是谁,该说什么?A.Who is it B.who are you用哪个比较合适?为什么? WHO IS IT是谁唱的快 为什么用who is it 而不用who are you? who is it from?是它是谁的? The flowerpot is broken,who knocked it over?为什么用over不能用off吗?为什么用over不用off？ It is I who am to blame.为什么who 后面用am 不用 is? who is it here is the door ------- .who is it the door ----- -----who is it 门铃响了,是谁呢? Who ever can it be ?那究竟能是谁呢? 为什么be不在can的后面呢 ?而在it的后面 谁可以解释一下句型我可以这样说吗 who ever is it ? 它究竟是谁 who is that?it must be Mary.为什么不能用she? 英语里面打电话说自己是谁,为什么不直接说I‘m ...而是用This is 或It's ... what it is?who it is? 老外问你是谁是不是说who is it?而不是who are you? 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 who is your favorite actor?回答为什么用It is Cheng Long It不是它的意思吗?who is your favorite actor?回答为什么用It is Cheng Long It不是它的意思吗? who is it和who it is哪个对?都什么意思.为什么who you are对