fall out of: 飞离，放弃
If you fall out of that tree and break you leg , dont come running to me.
如果你从树上掉下来摔断了腿，别跟我这哭哭啼啼的。
I fell out of my old habit.
我放弃了我的老习惯

run into: 偶遇
But at that size the ships run into problems.
但这样大的船将会遇到许多问题。
I unexpectedly ran into him on the street yesterday evening．
昨天晚上我在街上偶然碰见了他。