stop sb.from doing sth./ prevent sb.from doing sth./ keep sb.from doing sth.三者都表示“阻止某人做某事”,一般情况下可以通用.如果一定要找出意思上细微差别,如下：prevent sb from doing sth阻止某人做某事,让某人不做某事 stop sb from doing sth让某人不做某事 keep sb from doing sth让某人不做某事(保持不做某事,有个持续动作) 用法上的差别：在主动式中,stop sb.from doing sth.和prevent sb.from doing sth.中的介词from可以省略,但 keep sb.from doing sth.中的介词from不能省略（keep sb.doing sth.意思为让某人一直做某事）.在被动式中三个词组中的from都不能省.