I called Mary many times yesterday evening. But I couldn’t get through. Her brother _____ on the phone all the time.

A．talked

B．had talked

C．has talked

D．was talking

哌替啶的化学名为（）

A.17-甲基-3-羟基-4，5α-环氧-7，8-二脱氢吗啡喃-6α-醇盐酸盐三水合物

B.1-甲基4-苯基4-哌啶甲酸乙酯盐酸盐

C.17-甲基_3-甲氧基4，5α-环氧-7，8-二脱氢吗啡喃-6α-醇磷酸盐倍半水合物

D.4-二苯基-6-（二甲氨基）-3-庚酮盐酸盐

E.1-甲基-4-苯基-4-哌啶乙酸乙酯盐酸盐