AIDS researchers say they still have much work to do on a vaccine (疫苗) against HIV. But the first reports of some success have raised hopes. 1 The study was designed to test for two
---Mike seldom has breakfast at home, _______? --- _______ this morning. A. does he; No, but he did B. does he; No, he hasn’t C. has he; Yes, he has D. hasn’t he; Yes, he doesn’t