fall down pass

例句：

1. 1.The old man fell down when he triedto walk.
   老人尝试走路时摔倒了。
2. 2.The car suddenly fell down the hill.
   汽车突然从山坡上滑了下来。
3. 3. The housecollapsed after a strong wind hit it.
   房子在一阵强风中倒塌了。