In the book, we meet John Muir as a youth fearlessly climbing the roof of his house.
出自-2013年6月听力原文
Mountain climbing is becoming popular sport, but it is also a potentially dangerous one.
出自-2012年12月听力原文
At heights of over 18000 feet, people may be climbing in a constant daze(恍惚)
出自-2012年12月听力原文