She didn't want to fall down like other leaves.

　　她不想像其他樹葉一樣落下。

　　She saw the leaves fall down.

　　她看到樹葉飄落。

　　Lan said if her house could fly, it wouldn't fall down in an earthquake.

　　蘭說,如果她的房子能飛,就不會(huì)在地震中倒塌。

　　Why did it fall down?

　　它為什么掉了下來？

　　It can improve your balance by exercising your main muscles so that you can't fall down.

　　它可以通過鍛煉你的主要肌肉來改善你的平衡感，這樣你就不會(huì)摔倒。