internal void

例句：

1. 1.The company's headquarters are located in the heart of the city.
   公司的总部位于市中心。
2. 2. The book is written in English, so it's suitable for internal use only.
   这本书是用英语写的，仅供内部使用。
3. 3.The new building has an internal elevator system.
   这座新建筑有一个内部电梯系统。