Many people have cars in the city. But (污染) is a problem because of the cars. Nowadays some downtown(闹市区的) areas around the world don't have cars. These car-free zones(无车区) are areas for people, bicycles and (公共的) transportation only. Eight million people   (居住) in the center of London and another two million people go to work there every day. The downtown area is very (吵闹的) with hundreds of cars, buses and taxis, but there are (也) a lot of beautiful parks with free music concerts. Many people go there for a rest (在……之后) they get off work. Parts of Tokyo are always crowded with hundreds of people- but no cars! These modern car-free zones are (真正地) popular and people like shopping there. In the past, Bogota was polluted (因为) there were lots of cars and traffic. Now the downtown area is a car-free zone and the air is (干净的)! Many people don't have a car and half a million people take the bus to work. There are lots of stores. It's not (昂贵的).