fall off 是从某物上跌落下来,off有脱离的意思,比方说从树上掉下就可以用.
fall to 不是固定用法,就是掉到...的意思,比如 fall to the ground
fall down是跌倒的意思,表示失去原有的平衡,fall away
离开
All his old friends fell away from him.
他的老朋友全都离开了他.
消瘦
You'd scarcely believe anybody could fall away so rapidly.
你简直难以相信一个人会消瘦得这么快.但没有脱离支撑物.比如墨水瓶翻倒.fall asleep 入睡fall over 朝某方向 占据某位置