mary keeps talking about the party ,she had a very good time,didn't she?为什么用didn't而不是 hadn't?

mary keeps talking about the party ,she had a very good time,didn't she?
为什么用didn't而不是 hadn't?

之前的had 是have的一般过去式,所以用did.
当had做助动词是用hadn't
如果,请采用

因为she had a very good time中的had是实动词，并不是完成时态中的助动词