All her time _______ experiments, she has no time for films.

A．devoted to do

B．devoted to doing

C．devoting to doing

D．is devoted to doing

杠杆百分表测量杆与扇形齿轮杠杆臂之间是靠摩擦力联结在一起的，使用时不许扳动测量杆改变其角度位置和测量方向。