Bicycle sharing systems are also known as yellow bicycle programs, white bicycle programs, public bikes, or free bikes. They are increasingly popular in Europe now. Paris has the world's largest urban   cycle rental system. This is a bike rental station in Paris. The worker is showing how to use a new self-service bike. They say that Paris will become "a green capital of bikes" and they plan to park 20,000 bicycles at 1,600 stations. Paris created this plan to improve the city traffic environment and reduce the waste gas displacement  . At a rental station, you only have to put your credit card into the machine to rent a bike. It provides French, German, English and Chinese services. If you ride the bike for only 30 minutes to relax, you needn't pay for it. A two-hour bike rent only costs you 4 euros. These stations work for 24 hours every day, so a bike is rented for 10 to 14 times a day. In this way there are 200,000 people using bikes a day, In the past few years, Paris has encouraged its people to ride bikes, but something unhappy has happened now and then. Some people break the traffic rules during rush hours. Some park their bikes everywhere. So how to park bikes is a problem that Paris will face. But this project is still a helpful way to improve its traffic environment. Don't you think so? Paris built many rental systems to  _  .
relax travelers improve the environment reduce traffic accidents get money