一质量为m的小球,从离地面高H处由静止开始自由下落。不计空气阻力,以地面为零势能面,当下落到离地面的高度为h时,小球的机械能为[ ]
A.
B.
C.
D.
答案:A
可以通过肺部吸收,被吸收的药物不经肝脏直接进人体循环()
A.静脉注射
B.口服制剂
C.肌肉注射
D.气雾剂
E.经皮吸收制剂
A—3-1eg InterchangeB—peak periodC—absolute speed limit D—acceptable gapE—access F—accidentG—accident causeH—advanced public transportation servicesI—air resistanceJ—annual average daily trafficK—area traffic controlL—automatic vehicle monitoring systemM—banning of turning movementN—belt HighwayO—bike lane
( )可接受间距( )重点交通管制