Fill in the gaps with the words derived from the words given in brackets.
The London Underground
The London Underground was the first underground system in the world. It is over 140 years old. Its 1) .....................\(construct\) began in 1890. The system was opened in 1863 and its 2) ............ \(long\) was only 4 miles \(6\.5 kilometers\) running from the west of London to the city in the east. It was not very deep and steam trains were used. At the end of the 19th century most lines used 3) ................... \(electric\) to power the trains. 4) ...................... \(London\) called this system the Tube and it is still a very popular name for the London Underground.
Some of its deep stations were used for 5) ...................\(protect\) of the 6) ..................... \(city\) during World War II. And the tunnels of the 7) ...................... \(use\) Aldwych spur line were housing artifacts from the British Museum.
A great number of people use the underground system 8) .................... \(day\) because it connects 9) .............. \(near\) all the parts of this 10) .................\(wonder\) city. The London Underground carries over a billion passengers a year, or about 3 million every day.