keep doing sth 和continue doing sth 和 can't stop doing sth 有什么区别

keep doing sth 和continue doing sth 是同义词组,继续做（之前在做）的事
can't stop/help doing sth和can't wait to do是同义词组,忍不住或情不自禁去干什么
扩展：can't help do ,不能帮助做什么