2017年高考英语全国II卷第二部分第二节短文填空
第二节（共10小题；每小题1.5分，满分15分）
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。
In 1863 the first underground passenger railway in the world opened in London. It ran for just under seven kilometers and allowed people to avoid terrible 41 (crowd) on the roads above as they travelled to and 42 word. It took three years to complete and was built using an interesting method. This included digging up the road, 43 (lay) the track and then building a strong roof over 44 top. When all those had been done, the road surface was replaced.
Steam engines 45 (use) to pull the carriages and it must have been 46 (fair) unpleasant for the passengers, with all the smoke and noise. However, the railway quickly proved to be a great success and within six months, more than 25,000 people were using 47 every day.
Later, engineers 48 (manage) to construct railways in a system of deep tunnels (隧道), which became known to the tube. This development was only possible with the 49 (introduce) of electric-powered engines and lifts. The central London Railway was one of the most 50 (success) of these new lines, and was opened in 1900. It had white-painted tunnels and bright red carriages, and proved extremely popular with the public.