There must be many people ________ for their trains at the train station because of the golden week holiday.

A． are waiting

B．waited

C．to wait

D．waiting

下列关于哌替啶说法错误的是（）

A.哌替啶是一个合成镇痛药

B.本品为白色结晶粉末，易溶于水，易吸潮，遇光易变黄

C.因结构中含酯键，水溶液短时间煮沸马上分解

D.本品能通过胎盘，并随乳汁分泌

E.镇痛作用约为吗啡的1/10