Fill in the blanks with the words and expressions given below. Change the forms where necessary. be worth it, unlike, on the horizon, renewable, global, expensive, light up, powerful, replace, under way, generation, main, provide ... with, run out of, type, traditional, million, release, special, in the long run 1. I hope that people living in big cities can still see millions of bright stars 1 the sky on summer nights. 2. He wanted to sail around the 2 when he was young. 3. Wind is formed when the sun heats the air in some areas and air from cooler areas flows in to 3 the heated air. 4. Every four years, 4 of people watch the World Cup on TV with great excitement. 5. Do you know how to make use of 5 energy sources such as wind and wave power? 6. Dr. Smith's study 6 us with an answer to the question about the hot springs in this area. 7. My family has lived in this house for 7 and we don't want to move to any other place. 8. When oil 8 into the sea, the sea water becomes polluted. 9. As coal burns, it produces useful energy in the form of heat. The 9 use of heat from coal is the production of electricity. 10. Large cities always have lots of problems. When one is solved, there are often more 10 . 11. There were so many different 11 of bread that I didn't know which to buy. 12. He is very tall and needs a 12 bed and shower at home. 13. The cost of building or buying a racing car makes car racing one of the most 13 sports. 14. My father spent 10 thousand dollars to build the green roof, but he thought it 14 . 15. Maybe I am wasting my money having solar-energy systems installed, but I'm sure it's the best thing for me to do 15 . 16. It's time for us to use solar energy or wind energy now because we are 16 traditional energy sources. 17. 17 most other natural resources, such as coal and oil, forest resources are renewable. 18. As cities become larger and larger, the people living around them find it more and more difficult to keep their 18 way of life. 19. This car runs faster than before because they have installed a more 19 engine in it. 20. Talks between the two companies about a new development plan have been 20 for six months.