American universities are rushing towards a wireless future. They are installing networks

that let students and teachers surf(浏览) the Internet from laptop computers anywhere 【C1】______ campus. But professors say the technology 【C2】______ a growing challenge: Retaining their students' attention.

In a classroom at American University in Washington D.C., the benefits and drawbacks(缺点)of the new wireless world were 【C3】______ . From the back row of a lecture hall, more than a dozen laptop screens were 【C4】______ . As Professor Jay Mallek 【C5】______ on the finer points of an office budget, many students went online to surf the Net. Students write quick e-mails and send instant messages. A young man shows an 【C6】______ e-mail to the woman next to him, and then 【C7】______ read the online edition of The Wall Street Journal. Distraction(注意力分散) is 【C8】______ new. As long as there have been schools, students have whispered, passed notes and even 【C9】______ of the window and daydreamed. But the arrival of the laptop has introduced new 【C10】______ for diversion or distraction, and wireless introduces an even broader range of distraction.

This is 【C11】______ annoying for law professors, many of 【C12】______ still live in the world of paper. "This is something that 【C13】______ the students themselves," said Ian Ayres, professor at Yale Law School, who opposes the Internet's 【C14】______ into the classroom. Unless law students are fully 【C15】______ the class, he said, they miss out on the give and take of ideas in class discussion and do not develop the critical thinking skills that emerge from "deeply tearing apart a case." 【C16】______ , Professor Mallek at American University sees it differently. He said the benefits of the technology 【C17】______ the problems. He 【C18】______ that it might even be making him a better teacher. He takes the threat of 【C19】______ his students to e-mail and online newspapers as a 【C20】______ to keep lectures interesting and lively.

【C1】

A．in

B．on

C．at

D．around