There is one language used in every country in the world. It is everybody's second language. It is easy to understand, although you can't hear it. It is sign language.
For example, when you wave to a friend who is across the street, you are using sign language. When you smile at someone, you are saying, "I want to be friendly", but you are not using speech. You are using sign language. When you raise your hand in class, you are saying, "Please ask me. I think I know the correct answer." A policeman is using sign language when he holds up his hands to stop traffic. Even a baby can use sign language when she points at things that she wants.
Many years ago, a French priest (牧师) called Charles Michel invented a finger alphabet (字母表) for deaf people. It is still in use. People can make the sign for letters and spell words with their hands, and deaf people can read and understand them. Soon there were schools for the deaf in many countries. The only university for the deaf is Gallaudet University in Washington, D.C.
Today, in the US, there are special TV news programs for deaf people. The newsreader tells the news in sign language. At the same time. the words appear on the TV screen.
The actors in the National Theatre of the Deaf (NTD) don't spell every word. Sometimes they use hand signs. When they put one hand above and the other below, empty in the middle, it means sandwich. They can make a roof with their hands when they want to show a house. One finger in front of an actor's mouth can mean quiet. You can talk to people behind closed windows. And when you go swimming with your friends, you can have conversations under water.
B . 
C . 
