题目内容：

反义疑问句选择题
请先帮我看几道题目：
1 He said Mary had done it,____?
A hadn't she B hadn't Mary C didn't he D did he
2 It's my son's birthday next week,and i have to do my best for that,____?
A isn't it B is it C haven't I D don't I
这我特搞不清楚,麻烦简要地说明一下理由.