--Jack's never worked hard at English, _______?

-- _______ , so he can't answer the question in English, I think.

A．is he; Yes, he is

B．is he; No, he isn't

C．has he; Yes, he has

D．has he; No, he hasn't

社会保险稽核是指社会保险经办机构依法对（）情况进行核查。

A.社会保险费缴纳

B.社会保险待遇领取

C.社会保险费缴纳情况和社会保险待遇领取

D.社会保险基金管理