keep on:继续
eg.He kept on talking.他讲个不停.
keep oppen:处于开的状态
eg.We keep open house at weekends.周末我们随时欢迎客人光临.
keep closed:处于关（闭）着的状态
eg.keep your eye's closed.眼睛处于闭着的状态
keep open和keep closed是反义词