题目内容：

阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

You’ve probably seen the term extreme sports in magazines, heard about it on the evening news, and seen it 1. (advertise) in sporting goods stores. So, what exactly are extreme sports?

During the 1970s and 1980s, the term “extreme sports” 2. (use) for sports that were often dangerous and could result in injury or even death. Today, however, extreme sports also include 3. (activity) that give a feeling of adventure without 4. (necessary) putting your life in danger. For every extreme sport there is professional equipment that has been  developed 5. (protect) your body and improve your performance.

Extreme sports cover a wide 6. (vary) of activities. Some extreme sports have developed 7. a familiar activity, like mountain biking. Some extreme sports may not be well-known. Bouldering, for example, is a type of rock climbing in 8. no rope is used. It usually takes place in an area with large rocks or in climbing centers.

People have never stopped 9. (develop) new types of extreme activities. These sports are gaining 10. large audience and growing in popularity, especially among young people.