狼三则其一 少却的少:Stop sb. from ...三者区别。。。

stop 即是停止的意思。例如，在红灯前将车停下来，就叫做：stop the car before traffic light turns red.
prevent 即是防止的意思。例如，to prevent accidents from happening, public should be more cautious of their own safety.
protect 即是保护的意思。例如，women should protect themselves from family violence by voicing out through newspapers.

Stop sb. from doing sth.
停止...做什么(已经在做了,要停止)
The teacher wants to stop her students from jumping on the tables.

Prevent sb. from doing sth.
防止...做什么(还没有做,为了预防为主)
The teacher put a mat on the floor to prevent students from hurting themselves.

Protect sb. from ...
Protect sb. from being ...保护...
We should protect ourselves from scams.
The manager wants to protect her secretary from being fired.

Stop sb. from doing sth.
阻止某事(对已经发生的事情进行阻止)

Prevent sb. from doing sth.
阻止某事(事情还没发生，是预防发生的意思)

Protect sb. from doing
保护...免受...(和上两个短语不是一个意思)