依个人分析,楼主把We've(即We have的缩写)误写成了We're. 句中的run不是动词原型,而是其过去分词.只因其过去分词与原型相同. have been playing表过去某个时间开始终到现在一直...,而现在还在...强调是动作的持续进行.而have played表示“已经...”,强调动作已经完成.
We're run out of money to buy books有语法错误 We're running out of money to buy books We've run out of money to buy books we ran out of money to buy books就对了 have been playing一直在玩 have played玩过了