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 1863the first underground passengerrailway in the world opened in London. It ran for just under seven kilometersand allowed people to avoid terrible __61__(crowd) on the roads above as theytravelled to and ___62__ word. It took three years to complete and was builtusing an interesting method. This included digging up the road, ____63___(lay)the track and then building a strong roof over___64___ top. When all those hadbeen done, the road surface was replaced.

    Steam engines ___65__(use) to pull thecarriages and it must have been___66__(fair)unpleasant for the passsengers,with all the smoke and noise. However, the railway quickly proved to be a greatsuccess and within six months, more than 25,000 people were using___67__ everyday.

Later, engineers ____68___(manage) to construct railways in a systemof deep tunnels (隧道), whichbecame known to the tube. This development was only possible with the ___69___(introduce) of electric-powered engines and lifts. The central London Railwaywas one of the most ___70___(success) of these new lines, and was opened in1900. It had white-painted tunnels and bright red carriages, and provedextremely popular with the public.