下列所给的图象中能反映作直线运动的物体在2秒末回到初始位置的是( )
A:
B:
C:
D:
提起压在容器中水面上方的活塞,容器中的水发生汽化,如图所示。下列选项中,最能表示水汽化后相同空间内粒子分布的是( )
A. He is playing ping-pong.
B. They are climbing trees.
C. She is singing and dancing.
D. I'm doing my homework.
E. It's running on the grass.
— Do you like pandas?
— .( )