根据短文内容，用方框中所给单词的适当形式填空，每词限用一次。
Have you heard of “car sharing”? The idea of “car sharing” is becoming more 小题1: in Europe and the USA. “Car sharing” is that people drive together in the same car to work, instead of 小题2: their own cars.
On average , we drive our cars only one hour every day. The rest of the time we 小题3: park our cars in parking places and we have to 小题4: too much money in parking our cars in the city. To save money and help the environment, people 小题5: to share cars several years ago. ”Car sharing” is a good way for us to save money, time, and help the environment at the same time. What a great idea!
小题1:popular
小题2:driving
小题3:must
小题4:spend
小题5:began
题目分析：短文大意：本文主要介绍了在欧洲和美国更受欢迎的你听说过“汽车共享”。“ “汽车共享”对我们来说是省钱和省时的一种很好的方式，同时帮助环境。多么好的主意！
小题1:句意：“汽车共享”在欧洲和美国更受欢迎。根据more可知后面该填写形容词popular。
小题2:句意：而不是开他们自己的车。Drive a car开车，所填词跟在介词of之后，故填写driving。
小题3:句意：其余的时间我们必须在停车的地方停我们的车。所填词后有原形动词park，故填写情态动词must。
小题4:句意：我们不得不花太多的钱在城市停车。Spend…in doing sth花……做某事，所以填写spend。
小题5:句意：为了省钱，帮助环境，人们在几年前就开始分享汽车。根据several years ago 可知该用一般过去时，begin to do sth开始做某事，所以填写began。