是keep dancing 还是keep on dancing

是keep dancing 还是keep on dancing KEEP ON DANCING是什么意思? 是keep quiet还是keep quietly 为什么 是keep silent 还是keep silence 是keep balance 还是keep a balance 保持沉默是keep silent还是keep silence keep company是keep dogs company还是keep dogs companies keep silent还是keep silence keep health还是keep healthy keep diaries还是keep diary keep happily 还是keep happy Keep on dancing 和Keep on dance有什么区别 保持健康是 keep healthy还是keep health 保持健康是keep health 还是keep healthy? 是keep study hard还是keep studying hard? 是keep one's word还是keep one's words 处于开的状态是keep open还是keep opened? 是keep you update 还是keep you updated 呢,why?