Skin-diving（轻装潜水）is a new sport today. This sport takes you into a wonderful world. It is like a visit to the moon. When you under water， it is easy for you to climb big rocks， because you are no longer heavy.
Here， under water， everything is blue and green. During the day， there is much light. When fish swim nearly， you can catch them with your hands.
When you have tanks of air on your back you can stay in deep water for a long time. But you must be careful when you dive in deep water.
To catch fish is one of the most interesting parts of this sport. Besides， there are more uses for skin-diving. You can clean ships without taking them out of water. You can get many things from the deep water.
Now you see skin-diving is both useful and interesting.
46. Skin-diving is a new sport. It __________.
A. will take you to the moon.
B. will take you to a new world of land.
C. will take you to the mountains.
D. will take you to the deep water.
47. In deep water there is __________.
A. some danger
B. no light at all
C. a lot of blue fish
D. lots of green things
48. You can climb big rocks under water easily because ______.
A. you are very heavy
B. you are as heavy as on the land
C. you are not as heavy as on the land
D. you have no weight at all
49. With a tank of air on your back， you can __________.
A. catch fish easily
B. stay under water for a long time
C. climb big rocks
D. have more fun
50. Which of the following is not true？
A. Skin-diving is a new sport.
B. To have a skin-diving is like to visit the moon.
C. The only use of skin-diving is to have more fun.
D. Skin-diving is not only interesting but also useful.
You speak， write a letter， make a telephone. Your words carry a message. People communicate（交际）with words. Do you think you can communicate without words？ A smile on your face shows you are happy or friendly. Tears（眼泪）in your eyes tell others that you are sad.
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.
51. People communicate ________.
A. with words only
B. in many different ways
C. in letters and drawings
D. with smiles， tears and hands
52. Signs can carry as many _________ as words.
C. tears and smiles
53. Which of the following is not talked in the passage as which can help us communicate？
A. books and magazines