keep on doing 和keep doing 的区别是什么？

keep on doing 和keep doing 的区别是什么？

keep on 更加强调时间的间隔性和动作的反复性,及某人做某事的决心.
keep doing坚持做某事 
例句：
He kept talking until the meeting was over.他一直在说,直到会议结束.

He kept eating/ smiling/ walking.他一直在吃/笑/走.

She keep running她一直在跑（没停过）

He kept standing in the street .他一直站在大街上.


keep on doing 克服困难继续坚持


例句：
He kept on ringing me up,but I don't want to keep in touch with him any more.
他不断地给我打电话,可我不想和他保持联系了.


The boy kept watching the passing traffic at the gate.
这个男孩在门口不停地看着过往的车辆.

She kept on raising her hand她反复举手（不是一直举着手）


He kept on repeating these words over and over.他一遍又一遍重复这几句话.

1.keep on doing sth  
(1) 不断地或一直做某事(动作之间略有间隔)。如： 
He kept on looking at us. 他老是瞧我们。  
Don’t keep on asking questions like that. 不要老是问那样的问题。 注：此用法可与 keep doing sth 换用。  
(2) 继续做某事(即将一直在做的事继续做下去)。如： 
He kept on working after dark. 天黑了我们还继续干。
Don’t give up; keep on trying. 别灰心，继续努力。 注：这样的 keep on doing 有时可与 go on doing 换用。如：  
The boys kept [went] on doing their homework in spite of interruptions. 尽管有干扰，孩子们仍继续做自己的作业。 
2. keep doing sth  
(1) 不断地或一直做某事(动作之间略有间隔)。如：  
They kept talking about it. 他们一直在谈论此事。  
My shoe laces keep coming undone. 我的鞋带老是松开。 注：此用法可与 keep on doing sth 换用。
(2) 一直在做某事(无间隔)。如： 
He kept standing during the meeting. 开会时他一直站着。  
He kept hoping that they would have chance to come to China some day. 我一直希望什么时候有机会到中国来。  注：此用法通常不能与 keep on doing sth 换用