—Oh, really? What good news!
A:Because of
B:Thanks to
C:According to
A. sister B. father C. old D. brother E. worker
用30N的水平外力F,拉一静止放在光滑的水平面上质量为20kg的物体,力F作用3s后消失,则第5s末物体的速度和加速度分别是( )