老年人由于各器官功能衰退，用药剂量应为成人的
A.1/2
B.1/3
C.1/4
D.3/4
E.4/5
参考答案：D
— What took you so long?
— I got lost. I have no _____ of direction.[ ]
A. sense
B. ability
C. knowledge
D. feeling
中频噪声与高频噪声的分界线是( )。
A．100Hz
B．500Hz
C．1000Hz
D．5000Hz
