[originaltext] Port Glasgow, situated on a deep river near the sea, is a pla

Port Glasgow, situated on a deep river near the sea, is a place where ships have been built for many years. One of the earliest steam ships ever made was built in Port Glasgow in 1812. James Watt, who invented the steam engine, was born in Greenock — a town next to Port Glasgow on the river Clyde. One of the steam engines built by Watt was used to pump water out of the river. This steam engine gave Henry Bell, a local engineer, the idea of using steam to drive a ship. The ship that he built was called the "Comet". Although it was only a small ship, it was the first step towards the huge ships constructed in Port Glasgow today. In 1962, the citizens of Port Glasgow decided they would celebrate the one hundred and fiftieth anniversary of the building of the ’Comet’. Every one interested was given an opportunity to join in the celebration. The schools, youth organizations and churches agreed they would organize a grand parade to commemorate the day. It was decided that a new ship, looking exactly like the first ’Comet’, would be built. On the day of the celebrations, Saturday the 1st of September, 1962, the new ’Comets’ would be launched and would make a voyage repeating the original voyage made by the first ’Comets’ in 1812. The town councilors and some other important people invited to sail on this voyage were asked to wear clothes to look like people living at the beginning of the last century.
Questions 16 to 18 are based on the passage you have just heard.
16. What did the ship "Comet" use to propel itself?
17. When was the ship "Comet" built?
18. What can we learn about the anniversary of the building of the "Comet"?