如下图所示的三幅图,共同反映哪些物理知识?(至少写出两点)。
答:(1)地球上的一切物体都受重力作用(或重力方向竖直向下)
(2)重力势能和动能之间的相互转化(答案不唯一)。
It’s quite a time _____ Liu Xiang was injured in the foot, but we are sure it won’t be long _____ he returns to the track.
A.after; when
B.before; since
C.that; when
D.since; before
脑栓塞的常见病因为().
A.高血压
B.脑动脉硬化
C.脑动脉炎
D.心脏病
E.长骨骨折