Complete the following passage with the missing words

Complete the following passage with the missing words: cause, pollutions, traffic, problems, vehicles, parking 

Big cities have 1 ……………….with crowded streets, congested traffic, noise and air pollution. Every day, thousands of 2……………… fill the street, especially during rush hours. The large numbers of cars, buses and trucks 3…………………….so much congestion. No vehicles can move any direction.4 ………….. is another problem. There are not enough parking facilities, and when cars try to park on the streets, there is not enough room for 5……………….. Finally, the traffic adds to the problem of air and noise 6……………………