现在举一个20个大型建筑公司年平均资金周转期的例子。

Let's use an example the average annual inventory turnover in 20 large construction firms.

它们的氮含量均大于磷含量，周转期氮需13年比磷需12年为慢。

The turnover periods of N and Pwere 13 and 12 years respectively.

那么，开发的周转期又是怎样的呢——这应该被视作是一种中断吗？在成本方面带来了多少的增加？

So what about development Turnaround - should that be considered an interrupt and how much does it add to the cost?