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     Many people think that animals in the zoo are (1) h______ and lucky. But (2) m______ of them are sad.

Do you know why? Animals like tigers, (3) l______ and bears (4) u______ live in forests and (5) m______.

They can run, jump, play with their (6) c______ and catch small animals for food. But now they have to

(7) s______ in small rooms in the zoo. They don't have to (8) f______ food by themselves (9) b______ the

zoo keepers feed them. They do nothing but eat, walk and (10) s______ every day.

小球从空中某处从静止开始自由下落，与水平地面碰撞后上升到空中某一高度处，此过程中小球速度随时间变化的关系如图所示，则

A．在下落和上升两个过程中，小球的加速度不同

B．小球开始下落处离地面的高度为0.8m

C．整个过程中小球的位移为1.0m

D．整个过程中小球的平均速度大小为2m/s