A:What
B:How
C:Whe
D:Where
一颗自由下落的小石头,经过某点时的速度是10m/s,经过另一点时的速度是30m/s,求经过这两点的时间间隔和两点间的距离.(取g=10m/s2)
—The weather turns out to be fine.
— We can depend on ___ that the goods will be shipped to the flooded area on time.