在第3本 Notes Page 115 中有这样一句话我不是理解的很清楚，请指导：

"There is an inverse relationship between changes in assets and changes in  cash flows. In other words, an increase in an asset account is a use of cash, and a decrease in an asset account is a source of cash."

cash 不是本身也属于 current assets 中的一项吗？为什么cash减少asset反而增加呢？ 谢谢！