A:y1>y2>y3
B:y1<y2<y3
C:y2>y3>y1
D:y2<y3<y1
The fire was so damaging that the store had to close its doors.
起重机将一箱货物在5s内匀速提升了l5m,货物的速度大小为 ____ m/s,合 ____ km/h.