Question

为什么一般疑问句有时候用are提问，do回答啊

比如：
Are you at swimming?
Yes,I do.

Answer 1

这取决于动词的词性。be动词与形容词、名词类（包括名词、代（名）词、代名词等）等搭配，do或can等助动词与动词搭配。如：
Are you John? Is this pen yours?
Can I sit here? Do you know him?

另外，你的例句错了。应该是：
Are you at swimming? Yes, I am.

追问

那回答呢，按理说不通啊。
are提问do回答是可以的么?

追答

Are you John? Yes, I am.
Is this pen yours? No, it isn't.

Can I sit here? Yes, you can.
Do you know him? No, I don't.

Are you at swimming? Yes, I am.

追问

可以么？

追答

不可以。