A Paperless ClassroomImagine a classroom missing the one thing that’s long been considered a necessary part to reading and writing—paper. Not notebooks, no test paper. Nor are there any pencils or pens, which always seem to run out of ink at the crit

A Paperless ClassroomImagine a classroom missing the one thing that’s long been considered a necessary part to reading and writing—paper. Not notebooks, no test paper. Nor are there any pencils or pens, which always seem to run out of ink at the critical moment.A “paperless classroom” is what more and more schools are trying to achieve. Students don’t do any handwriting in this class. Instead, they use palm-size(手掌大小的),or specially-designed computers. The teacher downloads texts from internet libraries and sends them to every student’s personal computer.Having computers also means that students can use the Web. They can look up information on any subject they’re studying from math to social science. High school teacher Judy Harrell in Florida, US, described how her class used the Web to learn about the war in Afghanistan over one year ago. “we could touch every side of the country through different sites, from the forest to refugee camps(难民营)”,she said,” using a book that’s three of four years old is impossible.”And exams can go online too. At a high school in Tennessee, US, students take tests on their own computers. The teacher records the grades on the network for everyone to see and then copies them to his own electronic grade book.A paperless classroom is a big step towards reducing the waste of paper. High school teacher Stephanie Sorrel in Kentucky, US, said she used to give about 900 pieces of paper each week to each student. But, with all this technology, there’s always the risk that, the machines will break down. So, in case of a power failure of technical problems, paper textbooks are still widely available for these hi-tech students.
What does the phrase” break down” in the last paragraph possibly mean?

A.Go on working

B.Stop working

C.Start working

D.Keep working.

正确答案是B