What is the disadvantage for air transportation? ()
A. Quick but not safe
B. Less frequency
C. It can’t lift heavy goods
D. The highest cost in all transport modes
磁共振信号的采集与____是同时进行的()
A. 层面选择
B. 相位编码
C. 频率编码
D. 90°射频脉冲激励
E. 180°射频脉冲激励
低压脱水器用于小于()压力等级管网上.
A. 70Kpa
B. 10Kpa
C. 20Kpa
D. 50Kpa
六味地黄丸的配伍特点是________,________。