It's________of him to set his aim high but do little,so he is always leaving things undone.
化石是生物进化的唯一证据.(判断对错)
重为120N的物体在80N的水平拉力作用下向右作匀速直线运动,如图1所示,物体运动距离(S)﹣时间(t)图象如图2所示.物体所受到的摩擦力是 ____N.运动的速度是 ____m/s.
分解因式:m3﹣9m=____.