Questions 19 to 21 are based on the recording you have just heard.

Directions: In this section, you will hear three recordings of lectures or talks followed by three or four questions. The recordings will be played only once. After you hear a question, you must choose the best answer from the four choices marked A), B), C) and D). Then mark the corresponding letter on Answer Sheet 1 with a single line through the centre.
    19.
  • A The engineering problems with solar power.
  • B The generation of steam with the latest technology.
  • C The importance of exploring new energy sources.
  • D The theoretical aspects of sustainable energy.
    20.
  • A Drive trains with solar energy.
  • B Upgrade the city's train facilities.
  • C Build a new ten-kilometre railway line.
  • D Cut-down the city's energy consumption.
    21.
  • A Build a tank for keeping calcium oxide.
  • B Find a new material for storing energy.
  • C Recover super-heated steam.
  • D Collect carbon dioxide gas.