keep work on 还是keep on working?Cutting down trees后面用do 还是doe

keep work on 还是keep on working?Cutting down trees后面用do 还是doe 是keep dancing 还是keep on dancing keep going 还是keep on going? 是keep sharp eye on 还是keep sharp eyes on Fighting!keep on working hard! keep on doing是坚持还是继续 keep on to do对吗, If people keep cutting down the trees,animals will have nowh keep sb doing还是keep sb do ? ? ? ? ? ? ? ? ? Keep on Beliving、Keep on 是Don't cutting down trees. 还是Don't cut down trees. ? work on doing sth还是work on to do sth?