自行车装配小组，原来装配一辆自行车需5小时36分钟，现在装配一辆则只需用4小时。问原来装配60辆自行车的时间，现在可以多装几辆( )

A．84

B．48

C．24

D．16

An unstable upright equilibrium position on a vessel means that the metacenter is（）.

A.lower than the center of gravity

B.at the same height as the center of gravity

C.higher than the baseline

D.on the longitudinal centerline