2017全国卷2的语法填空

which became known to the tube. This development was only possible with the 69_i_n_tr_o_d_u_c_ti_o_n____ (introduce) of electric-powered engines and lifts. The central London Railway was one of the most 70_s_u_cc_e_s_s_fu_l____(success) of these new lines, and was opened in 1900. It had white-painted tunnels and bright red carriages,
In 1863the first underground passenger railway in the world opened in London. It ran for just under seven kilometers and allowed people to avoid terrible 61_c_r_o_w_d_s____(crowd) on the roads above as they travelled to and 62_f_ro_m______ work. It took three years to complete and was built using an interesting method.
Steam engines 65_w_e_r_e_u_s_e_d___(use) to pull the carriages and it must have been 66_f_a_ir_l_wenku.baidu.com______(fair)unpleasant
for the passsengers, 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__it_____ every day.Later, engineers 68__m_a_n_a_g_e_d_______(manage) to construct railways in a system of deep tunnels (隧道）,
and proved extremely popular with the public.
This included digging up the road, 63_la_y_i_n_g______ (lay) the track and then building a strong roof over 64_t_h_e_____ top. When all those had been done, the road surface was replaced.