Zip-lining( 滑索 道 )is becoming more and more popular in America. In zip- lining, people use a cable( 钢缆 ) to move very fast through the air. It is so exciting ! There are many zip lines around the country. About 200 zip lines belong to business companies. Others are in summer camps and school s. As zip-lining is becoming popular, more people are Get t ing hurt in Zip-lining than in other sports.Scientists studied zip line injuries that had happened in the past fif years. They found about 17, 000 people were hurt. Childre n and young people got hurt most often. Scientists say that more should be done to keep peopl e safe. If you are interested in zip-lining, you should first look at some websites. On those websites, you can find safe places to go. They also tell you what you should wear to keep you safe. There are also some rules about how to keep safe while you're riding zip lines. You should read all the rules c arefully and follow them before doing this exciting sport .