人造地球卫星从近地点向远地点运动时,___ _能转化为 能;从远地点向近地点运动时, 能转化为 能。
动;势;势;动
脑疝形成的机制关键在于()
A.颅内血容量增加
B.颅内内容物体积增加
C.颅内脑脊液量增加
D.腰、椎穿刺放出脑脊液
E.颅腔内压力分布不均
A “fifteen-pound” CO2 extinguisher is so called because().
A.there are fifteen pounds of CO2 in the container
B.the container,when full,weighs fifteen pounds
C.the pressure at the discharge nozzle is l5 psi
D.the empty container weighs fifteen pounds