语法填空专题训练课标全国IIIn 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 61 (crowd) on the roads above as they travelled to and 62 work
It took three years to complete and was built using 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 had been done, the road surface was replaced
Steam engines 65 (use) to pull the carriages and it must have been 66 (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 67 every day
Later, engineers 68 (manage) to construct railways in a system of