I live in a new town with my family. There are lots of tall buildings in the town. The streets are busy and the traffic is heavy, but the pollution is not very serious . In our town, more than half of the buildings have fifteen to thirty floors. Most of the people live in such tall buildings, but they don't have to climb the stairs. They use lifts to go up and down. Many restaurants, supermarkets, cinemas and theatres are in very tall buildings. They are big, bright and modern. So people enjoy eating, shopping, seeing films and watching plays in them. The streets in our town are wide, but because there are too many cars, they are still very busy. Sometimes when you come to the street crossing, you have to wait for the green lights for a long time. The people in our town never put _ everywhere or put dirty water into the river, so you cannot see much pollution in our town. I hope you'll come to visit our town if you like. The streets in the writer's town are very busy because   _  .
there are too many cars they are too wide many people walk on them the cars don't go fast