【2011．云南昆明】从A,B,C三个选项中选出能填入空白处的最佳答案。（共10小题，每小题1分，满分10分）
A green life sometimes just needs a good idea like sharing cars. It’s a new way of thinking. You can use a car but you don’t need to own it. Now the idea of “ car sharing” has become 51 in many countries.
As we know, most cars 52 in garages for much time. In fact, we drive our own cars 53 one or two hours a day on average(平均). When we don’t use them, we have to pay for parking and 54 things. That costs too much money. To 55 money, some people come up with the idea of “ car sharing”. If we share a car, we’ll only 56 when we use it.
