小刚比小军大4岁,小华比小军小3岁,小 刚和小华相差几岁?
3+4=7(岁)
火车在乎直的轨道上做匀速直线运动,其动能_______,势能________,机械能_______. (填“增大”、“减小”或“不变”)
治疗化脓性脑膜炎时头孢曲松钠的剂量是()
A.25mg/(kg·D.
B.50mg/(kg·D.
C.100mg/(kg·D.
D.150mg/(kg·D.
E.200mg/(kg·D.