pay for为.付钱
spend on 用法 spend on sth,在什么上面花了钱
spend in buying用法 spend in doing sth,做了啥事而花了钱你写的答案都错了，因为你时态没有看清楚啊。
应该是： paid for spent on spent in buying
呵呵.......哈。还真没去想时态问题呢。只不顾用法就这几个了