600 Read the text and answer the questions.
1 Why couldn't people build really tal buildings in the past?
2 When could people start building skyscrapers?
3 How did the invention of the elevator change the history of buildings?
4 Why did people want to build skyscrapers in cities?
5 Why are tal buildings called 'skyscrapers?
6 How fast did the Empire State Building grow?
7 What can you find in the Triumph of Astana in Kazakhstan?