英语翻译When you put up your hands in class,the teacher knows yo

英语翻译
When you put up your hands in class,the teacher knows you want to say something or ask questions.You shake（摇）your head,and people know you are saying "No".You nod（点头）and people know you are saying "Yes".Other things can also carry messages.For example,a sign at the bus helps you to know which bus to take.A sign on the door helps you where to go in or out.Have you ever thought that there are a lot of signs around you and that you receive messages from them all the time?People can communicate in many other ways.An artist can use his drawing to tell beautiful mountains,about the blue sea and many other things.Books are written to tell about all the wonderful things in the world and also about people and their ideas.Books,magazines（杂志）,TV,radio and films all help us communicate with others.They can help us to know what is going on in the world and what other people are thinking about.