Complete the sentences using the correct forms of the words and phrases in 1

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
   city dwellers      roof gardens      skyscraper      Traffic jam      urban centers   
1. is a serious problem in many big cities around the world.
2. The new underground has allowed  to get around more easily.
3. With the help of technology, people can now grow vegetables in  of high-rise buildings.
4. The  attracts people’s attention because of its unusual architecture.
5. More people are moving away from the  of large cities to the suburbs.