100 What Goes Up Must Come Down-Low

What Goes Up Must Come Down FOCUS Question Why do things move up or down?

焦点问题:事物为什么会上升或下降?

A girl throws a ball. It goes up in the air. A throw is a kind of push. A push moves things.

一个女孩在扔球。它升到了空中。 投掷是一种推。 推能移动东西。

The ball comes down. Gravity pulls it down. Gravity is a kind of pull. It can move things without touching them.

球下来了。重力把它往下拉。 重力是一种拉力。 它可以移动东西而不接触它们。

A boy pushes a car up the ramp. He lets go. Gravity pulls the car down. Gravity can be fun!

一个男孩推着一辆车上斜坡。 他放手了。重力把汽车往下拉。 重力可以很有趣!

A girl's legs push on some steps. Climb. Climb. Slide! Gravity pulls her down.

一个女孩在台阶上蹬着腿。 爬。爬。幻灯片!重力把她往下拉。

A boy pulls a sled up a hill. He lets go. Will the sled stay at the top of the hill? No. Gravity pulls the sled down.

一个男孩拉着雪橇上山。 他放手了。雪橇会停在山顶吗? 不。重力把雪橇往下拉。