问答题 Mailbox-watching in supposed to subside for high-school seniors after they receive their acceptance letters and make their college choices. Each summer, however, many an incoming freshman anxiously waits for the mailbox to produce another crucial envelope— the one holding the name of his or her future roommate. Many people assume that college freshmen pick their dormitory roommates, as upperclassmen are allowed to do. The converse is actually true. Very few colleges allow incoming freshmen any choice in dorm-room assignments. It’s inevitable that students will worry about potential problems with a roommate—a complete stranger. Students in the so-called millennial generation, in particular, are anxious about sharing a room with another person. Many have never shared a room at home. They are used to their rooms being their exclusive domains. For decades, residential-life offices have received late-summer telephone calls from worried students and parents. "People will read a name and address, and it fits into some category in their head," says Sarah B. Westfall, dean of students at Denison University in Ohio. They expect a diverse student body at almost any college, but many students fear diversity as much as they look forward to it. Any indication that a roommate’s life deviates from the familiar can heighten a student’s fear of the unknown. Online social-networking sites now allow students to get more of those indications than ever before. According to college officials, many incoming freshmen this year used Facebook and Myspace to do research on their future roommates. Since everything happens anonymously, normally passive students can spring into investigative action without having to approach a live person. On sites like these, anyone can post a profile of himself or herself free. Profiles can include photos, quotes, inside jokes, and lists of their favorite bands and TV shows. The idea is to maximize your attractiveness to people with tastes similar to yours.