Modals / verb modifiers are the verb forms such as can, could, may, might, shall, should, will, would, must,ought to, used to, need, had better, and dare. They are all used with other verbs to express ideas such as possibility, permission, or intention. In the given sentences, 'can' implies the order while 'ought to' is used to say that someone should do something because it is the best or most sensible thing to do.