_______ successful docking of Shenzhou VIII with Tiangong-I means that China has managed to take ________ first important step to establish its own space station.

A．/; /

B．A; a

C．The, a

D．The; the

吗啡与哌替啶比较，叙述错误的是()

A．吗啡的镇咳作用较哌替啶强

B．等效量时，吗啡的呼吸抑制作用与哌替啶相似

C．两药对胃肠道平滑肌张力的影响基本相似

D．分娩止痛可用哌替啶，而不能用吗啡

E．哌替啶的成瘾作用较吗啡弱