5.为了表示委婉或礼貌，避免提及动作执行者或说话者自己

You've been told many times not to make the same mistake．

你已被多次告知不要犯同样的错误。

Everybody is expected to obey the following rules．

希望大家遵守以下规定。

The control room may not be entered without permission．

非经许可，勿入控制室。