A、He is an educator. B、He is a writer. C、He is a librarian. D、He is a technician. C原文中，讲话者明确提到自己是一位图书馆管理员。因此答案为C。

Good morning, ladies and gentlemen. Today, I would like to talk about the building of a free digital library for our children.
    As parents, we really need to put the best we have to offer within the reach of our children. If we don’t do that, we’re going to get the generation we deserve. They’re going to learn from whatever it is they have around them.
    At the Boston Public Library, carved above their door is "Free to All. " I’m a librarian, and what I’m trying to do is bring all of the works of knowledge to as many people who want to read it as possible. And the idea of using technology is perfect for us. With the industry of the Egyptians, they were able to build the Library of Alexandria—the idea of a copy of every book of all the peoples of the world. The problem was you actually had to go to Alexandria to go to it. On the other hand, if you did, then great things would happen. If I’m successful, then you’ll actually come away thinking, yeah, we could actually achieve the great vision of everything ever published, everything that was ever meant for distribution, available to anybody in the world that’s ever wanted to have access to it. So the idea of electronic books is starting to come about.
    There’s a political and social question out of this. Is all of this…as we go digital, is it going to be public or private? There are some large companies that have seen this vision, that are doing large-scale digitization, but they’re locking up the public domain. The question is, is that the world that we really want to live in? What’s the role of the public versus the private as things go forward? So universal access to all knowledge—I think it can be one of the greatest achievements of humankind, like the man on the moon, or the Library of Alexandria. And as I said before, I’ll end with something that’s carved above the door of the Carnegie Library. Carnegie, one of the great capitalists of this country, carved above his legacy, " Free to the People. "
    Thank you very much.
    Questions 19 to 22 are based on the recording you have just heard.
    19. What is the recording mainly about?
    20. What do we know about the speaker?
    21. What did the Egyptians want to do when they built the Library of Alexandria?
    22. What have some large companies done with the publications in the world?