阅读短文，选择正确答案。

March 12th,

Dear Diary,

      Today was Tree-planting Day. It was also a good day for me. I was very happy. At about 6 o'clock, I

got up and put on my clothes. At 6: 30, I had bread and milk for breakfast. Then I went to school. The teacher

took us to a hill. He taught us to plant trees there. We liked to do this, so all of us planted trees happily. We

planted about one hundred trees this morning. We watered them. We hoped they can grow up quickly. At 1: 00

in the afternoon, I got home. My clothes were dirty, but I was happy.

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　John

1. When is Tree-planting Day?

A. March 12th.

B. March 8th.

C. March 9th.

2. What did John do today? 

A. He growed flowers.

B. He planted trees.

C. He washed clothes.

3. How did John feel?

A. He felt happy.

B. He felt angry.

C. He felt sad.

三相交流异步电动机机座的主要作用是（）。

A.磁路的一部分

B.是固定和支撑转子铁芯

C.要有足够的机械强度和刚度受力而不变形

D.是固定和支撑定子铁芯同时也是通风散热部件