As a young man, he began walking over tens of thousands of miles during his lifetime, through the south to Florida, the west to California and north to Alaska, where readers are taken a long and particularly hair-raising adventure on a large mass of floating ice
				出自-2013年6月听力原文
				As America's first environmentalist, John Muir lived his life forever daring to undertake new adventures
				出自-2013年6月听力原文
				Encourage people to undertake adventures
				出自-2013年6月听力原文