Rules are like rulers they tell us what we should do. We use signs to talk about rules. There are four kinds of signs. They are warning signs, information signs, direction signs, instruction (指令)signs. We can find a 'No smoking' in the library. It means we mustn't smoke. We can find a 'No swimming' sign by a river or a pool. It tells us we can't swim here. An instruction sign tells us how to do or not to do something. A direction sign tells us where to go. Signs are very important for everyone. They tell us what we must or mustn't do. We should obey the signs. If there are no signs on the road, accidents will happen everywhere. So we should follow the signs.

    Other things can also carry messages. For example, a sign at the bus stop helps you to know which bus to take. A sign on the wall of your school helps you to find the library. Do you ever notice that there are a lot of signs around you and you receive (收到) messages from them all the time? People can communicate (沟通) in many other ways. An artist can use his drawings to tell about beautiful mountains, the blue sea and many other things. Books are written to tell you about all the wonderful things in the world. Books, magazines, TVs, radios and films all help us to communicate with each other. They all help us to know what is going on in the world.