D. Listen to the passage and choose the best answer to the question (听短文和问题，选出最恰当的答案，短文和问题读两遍。)

  Usually, there are chairs and desks in every classroom. But a new study says, maybe students won’t need chairs any more. One day they will use standing desks. A research team in the US has made a study of primary school students. They find that if children use standing desks in classrooms, they can finish their classwork better than those who sit. Another study is made in high schools. It also shows the use of the standing desks can improve students’ attention. Many studies show that standing desks can help students lose weight and keep fit. Many teachers say using standing desks makes students listen more carefully and behave better. But a few teachers have their worries. It is not easy for them to see what every student is doing in class. Some students even walk around in the classroom. What’s more, the students are too tired by standing so long. Some parents also worry about it.

Questions:

16. F: According to the new study, what will not be used in the classroom?

17. M: Who had made the study on the use of standing desks?

18. F: What can standing desks help students do?

19. M: What do many teachers think of the standing desks?

20. F: Why do a few teachers have their worries?