阅读下面材料, 在空白处填入适当的内容(1个单词)或括号内单词的正确形式。

【小题1】 (sit) back in my seat, I can’t quite believe that I’m about to travel along the railway that many foreign experts 【小题2】 (claim) was ”impossible“. The train has been racing along 【小题3】 (steady) since it left Xining. All this time, the song ”Sky Railway” has been playing inside my head. The words “railways like 【小题4】 (mass) dragons are winding among the mountains” seem particularly vivid as I travel 【小题5】 the “roof of the world”.

I was one of the people 【小题6】 came from all parts of China to work on this railway. Taking years 【小题7】 (complete), the Qinghai-Tibet Railway is a record of all of our efforts to overcome 【小题8】 most difficult engineering challenges. How to protect the delicate ecosystem was among the top 【小题9】 (concern).

Now, thanks to so many workers’ efforts, the construction finished successfully. I am proud that we 【小题10】 (build) our “impossible” railway, and did so with the care that the environment deserves. It truly is an extraordinary “Sky Railway”.