I tried many ways I could think of____ (stop) the little boy from crying.
若x=2012,则代数式x2-2x+1x2-1÷x-1x2+x的值为( )
物体M在杠杆AOB作用下在如图所示位置静止,试在B点作出使杠杆在如图位置平衡时最小的力