4.Oh,there is someone at the door.Let me have a look.I think＿is my friend A that B it C she D he4.Oh,there is someone at the door.Let me have a look.I think＿is my friend A that B it C she D he 说出理由

4.Oh,there is someone at the door.Let me have a look.I think＿is my friend A that B it C she D he4.Oh,there is someone at the door.Let me have a look.I think＿is my friend A that B it C she D he 说出理由
4.Oh,there is someone at the door.Let me have a look.I think＿is my friend A that B it C she D he
4.Oh,there is someone at the door.
Let me have a look.I think＿is my friend A that B it C she D he 说出理由

4.Oh,there is someone at the door.Let me have a look.I think＿is my friend A that B it C she D he4.Oh,there is someone at the door.Let me have a look.I think＿is my friend A that B it C she D he 说出理由
用it.
不知道对方是谁、用it做指代、代指那个人.这是指示代词it的用法之一.

个人认为用it， 当不明白对象的性别时可以用It代替。

that，不知道对方性别。

B不知道对方是谁、用it做指代、代指那个人。这是指示代词it的用法之一。另外也可以指婴儿等 仔细看看指示代词的用法

B it
在不知道对方是谁或者不知道是个什么东西的时候都通用it。。。

B it
不知道对方是谁、用it做指代、代指那个人