Film has a much shorter history，especially when________such art forms as music and painting.                                                      (2012·新课标全国，32)

A．having compared to

B．comparing to

C．compare to

D．compared to

宇航员在某行星表面上从32m高处自由释放一重物，测得其在下落最后ls内所下落的高度为l4m，则该重物下落的总时间是______s，该行星表面的重力加速度是______m/s²．