胎儿4小时后方能娩出的分娩止痛可用
A．吗啡
B．阿司匹林
C．二氢埃托啡
D．芬太尼
E．哌替啶
参考答案：E
_____ is known to us all _____ Lu Xun is famous for his great works_____ a great writer.
A．It; that; for
B．It; that; as
C．As; / ; for
D．As; that; as
话筒是一种将声能转化成（）的器件。
A.电能
B.机械能
C.热能
D.光能
