下列药物属于妊娠慎用药的是（）
A.马钱子
B.天仙子
C.轻粉
D.麝香
E.桃仁
参考答案：E
Either you or one of your students___________ to attend the meeting that is due tomorrow.
A．is
B．are
C．have
D．be
截止阀，球阀，闸阀，旋塞阀都属于（）.
A.止回阀
B.切断阀
C.节流阀
D.减压阀
