英语演讲稿3分钟带翻译

　　HOW ARE TV PICTURES MADE?

　　A TV picture starts with a TV camera. Some TV cameras are big and some are small. The cameras in TV studios are big. Camera operators roll the big cameras around on wheels. There are usually several big cameras in a TV studio. Cameras used outside a TV studio are smaller. TV camera crews take the smaller cameras to news and sports events.

　　Some cameras send out live pictures to your TV set. Some cameras make videotapes that get played later on a television program.

　　All TV cameras need electricity to work. A camera operator points the camera at a scene. The camera picks up light from the scene. It changes this light into an electric signal called the video signal. A microphone changes the sound of people talking or music playing into an electric signal called the audio signal.