听力原文： Hi. My name's Tammy Mullen, and I'll be your guide on our campus tour. As we walk through the campus, I'll provide a bit of history about the college, and I'll describe some of our fine academic programs. Right now we're standing in the lobby of the Boyd Memorial Library. This library is named after Alexander Boyd, its first director and greatest benefactor. Thanks to Dr. Boyd's fine efforts, library development got off to a very good start here, and the Boyd Library now houses over 800, 000 volumes, including periodicals and newspapers. We also have more than 60, 000 maps and 2, 000 photographs in our collection. All of the library's collections are arranged for easy student access. There are comfortable study and reading lounges; in addition, more than 500 individual student study desks are located in the library within easy reach of reference materials and library stacks. Are there any questions about the library? Good. Then let's move on to the Cline Biology Building, If we're lucky, the greenhouse will be open and we can take a peek inside. Who is the speaker? A．A librarian. B．A tour guide. C．A professor. D．Alexander Boyd's secretary.