A、To limit the numbers of cars parked in the street. B、To prevent cars parked in the street from being stolen. C、To make it conv

City traffic is a great problem. More cars are produced every year and the streets are getting more and more crowded. So during "rush hours," when people are going to or from their work, traffic is brought to a standstill. It has been suggested that commuters should share their cars and give each other lifts. It is an excellent idea, however, so far nobody has been able to think of a way to compel people to do so.
    To discourage motorists from leaving their cars in the struts all day, parking meters are used. When you park at a meter, you will pay a coin. This pays for a certain amount of time. The meter records this and it shows when the time that you have paid for is finished. If the car is still there then, you have to pay a fine.
    Traffic wardens look after the meters. They walk around the streets and cheek that every meter shows that money has been paid for the car parked there. If a meter registers "time expired," the motorist who has left his car there is fined. Of course, the traffic warden cannot wait for the owner of car to return. He carries a block of printed forms, and on one of these he writes down all the details, such as the registration number of the ear, where it is parked, how much the driver must pay and where he must send the money. He leaves this form on the car where the driver will be able to see it easily; he usually pushes it under one of the windscreen wipers so that it will not blow away. And in case it rains before the motorist returns, the form is put in a little plastic envelope to protect it. When the driver comes back, he gets an unpleasant surprise, but it is his own fault for leaving his car too long at a parking meter.