Hello! I'm Victor.I have a bed, a desk, two chairs and a computer in my bedroom.My bed is small but very nice.It's blue because I like blue very much.My desk is big.It's white.You can see a computer and so many books on it.I do my homework here.I have two chairs.One is big and one is small.The big one is near the bed.The small one is near the window.I like my room.

一物体沿半径分别为r和R的半圆弧由A经B运动到C，经历的时间为t，如图所示，则它的平均速度和平均速率分别是（  ）

阅读短文，判断正误。

    I have a happy family. There are five people in my family. My grandpa and my grandma are very old, they like watching TV very much. My father is a doctor,  and my mother is a nurse. They work hard. I'm a student in Grade Three. I love my family.