我们通常用you来谈论人们，包括说话者和听者：
You can buy this book anywhere >This book is on sale everywhere.
You can’t park here >Parking is not allowed here.
They don’t let you smoke in here >No smoking here.
2.We use they or them to talk about people in general:
我们通常也用they或者them来谈论人们：
They serve good food here.
Ask them for a cheaper ticket.
3.… especially about the government and the authorities:
特别是关于政府或者权威
They don’t let you smoke in here.
They are going to increase taxes.
They are building a new motorway.
They say it’s going to rain tomorrow.