secondary to primary turn ratio

例句：

1. 1. The primary focus of the project is to improve the efficiency of production processes.
   该项目的主要目标是提高生产过程的效率。
2. 2.The secondary school students are preparing for their entrance exams.
   中学生正在为升学考试做准备。
3. 3.The secondary market is where people buy and sell goods that are not yet on the main market.
   次级市场是人们买卖那些还没有在主要市场上出售的商品的地方。