A、$1 million. B、$2 million. C、$3 million. D、$4 million. B录音提到“通常买纸质书总共约花费800万美元，而网络课本花费不到600万美元”，所以使用电子课本学校可节省约200万美元，正确答案是B。

Digital textbooks are transforming the way many students learn. All the Fairfax County Public Schools have begun using online course material for their middle- and high-school students. [3]This school year, the schools shifted from hard cover to electronic textbooks for social studies in its middle and high schools. The switch came after digital books were used in 15 schools last year. "Our students come to us technologically ready to use resources from a variety of different places," says Assistant Superintendent Peter Noonan. "There’s a significant financial benefit as well. Usually it is between $50 and $70 to buy a textbook for each student," Noonan says, [4] "which adds up to roughly $8 million for all of our students. We actually have purchased all of the online textbooks for our students for just under $6 million."
3. What happened to the schools in Fairfax County this school year?
4. How much have schools saved with digital textbooks?