keep on是指持续不断做某事,或者坚持做某事.
比如：If you keep on singing,they'll ask you to leave.如果你继续唱,他们会要求你离开的.
这句中的keep on是不能用其它几个词组代替的.
或者：I kept on trying,but it still didn't work.我不停地试,但还是不管用.
move on是指move forward,向前发展或推移,一般指人经历了一些事情之后,放下过去向前走的意思.
比如,As time moved on,he gradually left her behind his back.随着时间的推移,他慢慢把她忘记了.