presence indicator

例句：

1. 1. The presence of the new product has increased sales by 20%.
   新产品的出现增加了20%的销售额。
2. 2.The presence indicator is a crucial tool for measuring employee engagement.
   存在指示器是衡量员工参与度的关键工具。
3. 3. The company uses this device to indicate the presence of employees in different locations.
   公司使用这个设备来指示员工在不同地点的存在。