（原文标题：Bison boils to death in Yellowstone hot spring in front of tourists） 免责声明：本内容来自腾讯平台创作者，不代表腾讯新闻或腾讯网的观点和立场。

黄石超级火山在过去210万年里喷发过三次，最近一次是在64万年前。人类历史上还没有经历过黄石火山喷发。

The Yellowstone wolf project has been a valuable experiment to help biologists decide whether to reintroduce wolves to other parts of the country as well. 28.What is the text mainly about?