质量为m的物体,从静止出发以g/2的加速度竖直下降h,下列几种说法正确的是( )A.机械能增加了 B.动能减少了 C.机械能减少了 D.重力势能增加了 答案:C解析:
第二节 语法和词汇知识(共15小题;每小题1分,满分15分)
从A、B、C、D四个选项中,选出可以入空白处的最佳选项,并在答题卡上将该项涂黑。
--- It’s reported that more than 200,000
people lost their lives in Haiti Earthquake.
--- Yes, ______ news came as ______ shock
to us.
A.the ,
a B. the,
the C.
a, a D. a,
the