prevent sb. (from) doing sth （from可省略） 等于keep sb. (from) doing sth（from可省略） 还等于什么prevent sb. (from) doing sth （from可省略）等于keep sb. (from) doing sth（from可省略） 还等于什么?我只记得

prevent sb. (from) doing sth （from可省略） 等于keep sb. (from) doing sth（from可省略） 还等于什么
prevent sb. (from) doing sth （from可省略）
等于keep sb. (from) doing sth（from可省略）
还等于什么?我只记得是** sb. from doing sth（from不可少）

stop sb.from doing sth