They must have played computer games for several hours,didn'

they must have played computer games for several hours,haven't they?他们肯定玩了几小时的电脑,不是么?提问用的是完成时,所以反问也用完成时 如果反问要用一般过去式的话,应该是 they must played computers ,didn't they?他们肯定玩过电脑了,不是么?但是此句有for several hours,所以只能用完成式,只能改反问部分而不能把前面的完成式改掉