频谱多普勒超声可直接测量的血流参数是()
A.阻力指数(RI)
B.压力阶差(PG)
C.搏动指数(PI)
D.收缩/舒张期速度比(S/D)
E.收缩期峰值速度(Vs)
参考答案:E
What the children in the poor mountain village need ________ textbooks. [ ]
A. is
B. are
C. has
D. have
在近距离狭窄空间或较长时间持枪时应运用()。
A.双手腹前戒备
B.高姿戒备
C.低姿戒备
D.平肩戒备