礼貌是指人与人的交往应通过（）体现相互尊重和友好。
A、所处的环境
B、职位的高低
C、交谈时间量的大小
D、语言、表情、行为
参考答案：D
可制成含毒性药物散剂的药物是
A．冰片与薄荷脑 B．黄芪与白术 C．金樱子 D．马钱子 E．甘草与滑石粉
Loran-C uses the multiple pulse system because（）.
A.Less signal energy is necessary for receiver operation
B.More signal energy is available at the receiver
C.It significantly increases the peak power
D.It increases the signal capacity
