摔倒是fall还是fell donw ？为了直观的对比，我们分别把各自的含义了解一下：
fall
v.落下；下落；掉落；跌落；突然倒下；跌倒；倒塌；下垂；低垂
n.落下；下落；跌落；掉落；(雪、岩石等的)降落；发生；秋天
1.
Totally exhausted, he tore his clothes off and fell into bed
他疲惫至极，扯下衣服，一头倒在床上。
柯林斯高阶英汉双解学习词典
2.Output will fall by 6%产量将减少6%
fell down
(向下游)流下；〔美俚〕失败；跌倒；同“fall”
1.house fell down.
房子倒塌了。
2.
He fell down and injured himself.
他跌伤了。
相比之下，突然的摔倒用fell down更合适