6.421 Read the text and answer the questions.
Why couldn't people build really tall 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?
S Why are tall buildings called 'skyscrapers'?
6 How fast did the Empire State Building grow?
7 What can you find in the Triumph of Astana in Kazakhstan?