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。 Going to Mount Huangshan reminds me of the popular Beatles' song "The Long and Winding Road". ___ is so breathtaking about the experience is the out-of-this-world scenes. The rolling sea of clouds you see once you are at the top will remind you how tiny we ___ (human) are. The hot spring at the foot of the mountain is something you must try after the climb. It will ___ (undoubted) help you get refreshed! The amazing thing about the spring is that the colder the temperature gets the ___ (hot) the spring! Strange, isn't it? But that's how nature is-always leaving us ___ (astonish). What comes next is the endless series of steps. You can't help wondering how hard it ___ people then to put all those rocks into place. Though it is the only unnatural thing on your way up the mountain, still it highlights the whole adventure ___ offers a place where you can sit down to rest your ___ (ache) legs. As the song goes, this long and winding road "will never disappear", and it will always stick in the visitor's memory. It sure does in ___ (I). While you're in China, Mount Huangshan is ___ must to visit!