题目内容：

Skin-diving (潜水) is a new sport today. This sport takes you into a wonderful new world. It is like a visit to the moon. When you are under water， it is easy for you to climb big rocks (岩石) ， because you are no longer heavy.

Here， under water， everything is blue and green. During the day， there is plenty of light. When fish swim nearby， you can catch them easily with your hands.

When you have tanks (罐) of air on your back， you can stay in deep water for a long time. But you must be careful when you stay in deep water.

To catch fish is one of the most interesting parts of this sport. Besides， there are more uses for skin-diving.

1.By skin-diving you can get into a wonderful world.

2.Skin-diving is to visit the moon.

3.You cannot catch fish in the sea during the day.

4.With tanks of air on your back you can stay in deep water.