题目内容：

Sitting on a chair all day in school can make anyone want to move around. So, more and more teachers are letting students have a ball. By sitting on exercise balls instead of chairs, teachers find students' posture (姿势) and attention improve.

Dottie Pownall, a fifth-grade teacher in West Virginia, USA, has been using balls as chairs since December 2008. "The students love them", she says. Pownall took a survey of her students. She found that 80% of the students thought sitting on the balls helped them pay more attention to what they were learning.

The teacher, Pisa Witt, felt so strongly about the use of balls as chairs, she started Witt Fitt. This company encourages the use of the balls. And the company educates not only teachers but also students on how to use them. "Our products are used in 24 states, three provinces in Canada, Puerto Rico ('波多黎各) and Japan," says Witt. "Research shows that sitting on the balls makes them sit up straighter. You can slouch (低头垂肩地坐) on a ball," says Witt, "but it feels awful." Because the students are moving, their blood (血液) increases. That carries more oxygen (氧气 to the brain (大脑), so the kids have more energy and can focus longer.

"Furthermore, they're fun." says Pownali.

1. What will happen if a student sits on a chair all day in school? The student will _________.

A. pay more attention to his lessons                B. be fun

C. like to move around                         D. sit up straighter

2. How long has Dottie Pownall used the balls?

A. About three years.                       B. Only one year.

C. In 2008.                                 D. Since he was a fifth-grade teacher.

3. In how many countries are the balls used as the students' chairs?

A. Four.        B. Three.           C. Two.         D. One.

4.Teachers choose balls instead of chairs because sitting on balls helps the kids___________.

A. improve the students' posture and attention         B. slouch on the chairs

C. have fun                                    D. Both A and C are correct answers.

5.Which is better for kids to study in class, sitting on a chair or sitting on a ball?

 A. Sitting on a chair.     B. Sitting on a ball.

C. They are the same.    D. We don't know.