①stop/keep/prevent…from…意思是“阻止……去做……”,动词所接的宾语是要被阻止的对象.而
protect…from…中,动词所接的宾语是要被保护的对象.
②被动用法相同.stop/prevent…from…中使用主动语态时,可省略介词
from,而词组keep…from…中的from不可省略.但在被动语态中from均不可省略.例如：He tried his best to
stop/prevent her (from)going to the south ,but he
failed.他尽力地去劝阻她去南方,但是他失败了.［stop/prevent sb. (from) doing sth.］In order
to keep her from going out, he locked the door.为了阻止她外出,他把门锁上了.（keep sb.
from doing sth. from不可省略）
