fall off；fall down；fall onto；fall into

fall off；fall down；fall onto；fall into

  fall off用作及物动词，表示“从……上落下，掉下，摔下”。如：

The house moved and a few pictures fell off the wall，but that was all．

房子动了动，几幅画从墙上掉了下来，就这些。

He had fallen off a ladder and hurt his leg． 他从梯子上摔下来，伤了腿。

有时，它也可用作不及物动词，表示“落下，掉下，脱落”；也可表示“减少，越来越少”。如：

I watched all the glasses that were on the table fall off． 我看着桌子上的杯子全掉下来。

His supporters were falling off． 支持他的人越来越少了。

  fall down通常用作不及物动词，表示“（人）跌倒，摔倒，绊倒”或“（房屋等）   倒塌”。如：

The old lady fell down in the street and broke her leg．那老太太在街上跌倒了，摔坏了腿。

  fall onto意为“掉到……上”，其中onto为介词，也可用to。如：

The books fell off the desk onto／to the ground． 书从桌上掉到了地上。

  fall into意为“掉到……里陷入（困难）”等，into是介词。如：

fall into the river            掉进河里