Let me tell you my pen friend Ivan. He is 12 years old. He likes playing football. He usually play football with his friends at weekends.
Ivan lives with his father and mother in a city in France. They have a dream home with five rooms, a swimming pool and a garden. They often have a party in the garden at weekends. They like to help their neighbours. His home is not near his school, so Ivan takes a bus for an hour and then walks for 10 minutes to school. There is a Basketball Club near his school. He likes play basketball in the club.
   Ivan's father is a worker. He is busy. Ivan's mother is a doctor. She is nice to the patients. Ivan wants to be a teacher when he grows up. I want to be a teacher, too. Every month Ivan writes two letters to me. He'll come to Suqian next year. We'll meet then.

一台时钟的分针长6厘米，它走过2圈走了（ ）厘米

物体受到三个大小分别为3N、4N、5N的共点力作用，这三个力合力的最小值是（　　）

I have to see the doctor because I ________ a lot lately.