—Well, ________ this sweater________ that one is fit for her. They're too big.
A:both; and
B:either;or
C:neither; nor
D:not only; but also
写出下面数的因数和倍数(倍数写出5个)
9的因数____ 9的倍数____
如图所示,一轻质弹簧上端悬挂于天花板,下端系一质量为m1=2.0kg的物体A,平衡时物体A距天花板h1=0.60m.在距物体A正上方高为h=0.45m处有一个质量为m2=1.0kg的物体B,由静止释放B,下落过程某时刻与弹簧下端的物体A碰撞(碰撞时间极短)并立即以相同的速度运动.已知两物体不粘连,且可视为质点.g=L0m/s2.求: