4. Complete the sentences. Use the comparative or the superlative form of the words in brackets.

1. Canada is colder than Mexico in winter. 2. The Atacama Desert in Chile is the driest place on Earth. 3. Cairo is more crowded than Athens. 4. The weather in Madrid is much warmer than in London. 5. Traffic in New York is worse than in Chicago. 6. Mount Everest is the highest mountain in the world. 7. Greenland is the largest island on Earth. 8. The Mayan civilisation is older than the Aztec civilisation. 9. Europe isn't as big as Asia. 10. The Amazon is the longest river in South America. 11. The Pacific Ocean is deeper than the Atlantic Ocean. 12. Australia is the smallest continent in the world.