阅读下面的文言文，完成小题。

    蒋贵，字大富，以燕山卫卒从成祖起兵。积功至昌国卫指挥同知。从大军征交阯及沙漠，迁都指挥佥事，掌彭城卫事。

    宣德二年，四川松潘诸番叛，充右参将，从总兵官陈怀讨之。募乡导，绝险而进，薄其巢。一日十数战，大败之。进都指挥同知，镇守密云。七年复命为参将，佐怀镇松潘。明年进都督佥事，充副总兵，协方政镇守。又明年，诸番复叛，政等分道进讨。贵督兵四千，攻破任昌大寨。会都指挥赵得、宫聚兵以次讨平龙溪等三十七寨，斩首一千七百级，投崖坠水死者无算。捷闻，进都督同知，充总兵官，佩平蛮将军印，代政镇守。

    英宗即位，以所统皆极边地，奏增军士月粮。正统元年召还，为右都督。阿台寇甘、凉，边将告急。命佩平虏将军印，帅师讨之。贼犯庄浪，都指挥江源战死，亡士卒百四十余人。侍郎徐晞劾贵，朝议以贵方选军甘州，势不相及。而庄浪乃晞所统，责晞委罪。置贵不问。

    明年春，谍报敌驻贺兰山后。诏大同总兵官方政、都指挥杨洪出大同迤西，贵与都督赵安出凉州塞会剿。贵至鱼儿海子，都指挥安敬言前途无水草，引还。镇守陕西都御史陈镒言状，尚书王骥出理边务，斩敬，责贵立功。贵感奋，会朵儿只伯惧罪，连遣使入贡，敌势稍弱。贵帅轻骑败之于狼山，追抵石城。已，闻朵儿只伯依阿台于兀鲁乃地，贵将二千五百人为前锋往袭。副将李安阻之，贵拔剑厉声叱安曰：“敢阻军者死！”遂出镇夷。间道疾驰三日夜，抵其巢。阿台方牧马，贵猝入马群，令士卒以鞭击弓韣（dú，弓袋）惊马，马尽佚。敌失马挽弓步斗贵纵骑蹂击指挥毛哈阿奋入其阵大败之复分军为两翼别遣百骑乘高为疑兵转战八十里。会任礼亦追敌至黑泉，阿台与朵儿只伯以数骑远遁，西边悉平。

    十四年正月，贵卒，年七十。赠泾国公，谥武勇。

（节选自《明史·蒋贵传》，有删改）

    Now many young people are traveling around the world on their own, not because they have no one to travel with, but because they prefer to go alone．

     Kristina Wegscheider from California first traveled alone when she was at college and believes that it is something everyone should do at least once in their life. “It opens up your mind to new things and pushes you out of your comfort zone.” Wegscheider has visited 46 countries covering all seven continents(洲)．

    In foreign countries, with no one to help you read a map, look after you if you get ill, or lend you money if your wallet is stolen. It is challenging. This is what drives young people to travel alone．It is seen as character building and a chance to prove that they can make it on their own．

    Chris Richardson decided to leave his sales job in Australia to go traveling last year．He set up a website, The Aussie Nomad, to document（记录） his adventures. He said he wished he had traveled alone earlier. “The people you meet, the places you visit, or the things you do, everything is up to you and it forces you to grow as a person,” said the 30-year-old．

    Richardson describes traveling alone like “a shot in the arm”, which “makes you a more confident person that was ready to deal with anything”. He said: “The feeling of having conquered something on my own is a major part of what drives me each day when I'm dealing with a difficult task. I walk around with my head up because I know deep down inside that nothing is impossible if you try.”

    The great 19th century explorer John Muir once said: “Only by going alone in silence can one truly get into the heart of the wilderness.