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     1     (crowd) on the roads above as they travelled to and     2     work. It took three years to complete and was built using an interesting method. This included digging up the road,    3     (lay) the track and then building a strong roof over    4     top. When all those had been done, the road surface was replaced.

Steam engines     5     (use) to pull the carriages and it must have been    6     (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     7    every day.

Later, engineers     8     (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     9     (introduce) of electric-powered engines and lifts. The central London Railway was one of the most     10     (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.