As high school students flock to social networking sites, campus police are scanning their Facebook and MySpace pages for tips to help break up fights, monitor gangs and prevent crime. Some students object to police looking over their shoulders. But officers responsible for school safety say routine checks of the online forums often add to the knowledge they obtain from hallways or schoolyards. In recent years, school administrators have blamed some campus fights on Internet conflicts and urged parents to keep watch on their childrens computer activity. But students who use the Web to let their 500 closest friends know what they are doing at all times are sometimes surprised that police are watching, too. Police dont have special privileges on Facebook or MySpace. Students who want to go unobserved can change privacy settings so that their profiles are displayed only to a list of approved people. But the default(默认)settings leave those profiles open to many Internet users(in the case of Facebook)or all of them(in the case of MySpace). Employers and college admissions counselors have examined online profiles of student applicants for some time. Police across the country have been doing the same for the past two or three years, said Kevin Quinn, a spokesman for the Minnesota-based National Association of School Resource Officers. "If youre already familiar with the technology, it doesnt take you but a couple of minutes to hook into the student population and keep an eye on things," Quinn said. An expedition into a thicket(丛林)of MySpace profiles found high school students discussing drugs, sex and fights. It was all publicly available(although in language that caused a reporter to blush). Late last month, Fairfax County police announced the arrests of seven Chantilly area teenagers for trying to recruit Franklin Middle School students to a gang. That investigation was aided when a student showed the school resource officer gang symbols littering one of the suspects MySpace profiles. Fairfax police say they pride themselves on addressing issues in schools before they develop into major problems. Keeping an eye on Facebook and MySpace has become an extra tool in that effort, they said. Police officers scan social networking sites like Facebook or MySpace because_____.