题目内容：

听下面一段独白，回答以下小题。

1.How long have Earth Boxes been in market?

A.About 15 years. B.About 25 years. C.About 30 years.

2.What can Earth Boxes be used to do in poor countries?

A.Solve hunger problems.

B.Improve soil conditions.

C.Teach students science.

3.What is the advantage of Earth Boxes?

A.Saving much space.

B.Purifying much water.

C.Making crops grow fast.

4.Why are Earth Boxes used in middle school?

A.To learn math well.

B.To grow vegetables.

C.To do some experiments.