你老是丢三落四的。

You are always leaving something.

为什么你总是丢三落四的？

Why are you always losing things?

你那儿子丢三落四又把钥匙给忘了。

Your scatty son has forgotten his key again.

他们知道，我们总归要跌跌撞撞，磕这摔那，办事不力，丢三落四的。

They knew we would always fall down, drop things, be ruined, and forget.