Children are not always permitted to play computer games.意思是,不要总是允许小孩子玩电脑游戏.
英语中常把 always ,never ,often,usually等副词放在be 动词,助动词 或情态动词之后,行为动词之前.此句话属于部分否定.全部否定应该用never
Children are never permitted to play computer games.意思是：决不能允许小孩子玩电脑游戏