Câu 20 :
1. Read the article above. Match pictures A-D with paragraph 1-4.
(Đọc bài báo trên. Ghép hình ảnh A-D với đoạn văn 1-4.)
1. The hot-air balloon was the first form of flying that carried people. The first passengers were a sheep, a duck and a chicken! Then a few weeks later, on 21 November 1783 in France, a balloon carried two people.
2. The hot-air balloon uses science in a very easy but clever way. Hot air rises in colder air because it is lighter and less dense, just like the way our body floats on water.
3. The hot-air balloon has three main parts. There is a balloon envelope - this holds the air. At the top, there is a valve. Under the envelope, there is a burner. This uses propane gas to heat the air in the balloon. There is a wicker basket to carry passengers.
4. When the pilot wants the balloon to go higher, he turns up the gas to make the air hotter. To go down, he opens the valve at the top of the balloon. Some hot air leaves the balloon and it goes down.
