读短文，选择正确的答案。

      It's Sunday today. It's fine. There are a lot of people in the park. Some girls are flying kites. A young man

is playing balls. Long Long is playing football. I am watching TV in the room. Mei Mei is doing her homework

at home.

1. Is it fine?

A. Yes, it isn't.

B. No, it is.

C. Yes, it is.

2. Who is playing balls? 

A. Long Long.

B. I.

C. A young man.

3. Who's in the park?

A. A lot of people.

B. Some trees.

C. Some boats.

4. What do you do on Sunday?

A. Watch TV.

B. Play computer games.

C. Do homework.

5. Who is flying kites?

A. Long Long.

B. Mei Mei.

C. Some girls.

原子的种类决定于原子的（　　）

A．质量数

B．质子数

C．中子数

D．中子数和质子数