A、The guided tours. B、University Books. C、The Student Federation. D、A volunteer group. B浏览选项时如果发现第一题选项为机构组织名称的短选项，听音时要高度注意对话开头部分

M: Hello, University Books. Tim Weber speaking.
W: Hi, Tim, this is Ruth.
M: Oh, hi, Ruth, What’s up?
W: Well, the Student Federation needs a couple of volunteers to give guided tours to the new students next week. Would you be able to help out?
M: That depends on the days you have in mind. I’m working here full-time before classes begin. It’s really busy now, with all the textbook orders coming in, but I do have some time off.
W: What about Saturday-? Most new students arrive on the weekend.
M: Sorry, I have to work all day Saturday. How about Thursday and Friday? I’ve got both mornings free.
W: I don’t have the schedule on me. Ken’s got it. Maybe you ean set something up with him.
M: I’ll only be able to spare a couple of hours, though.
W: No problem. I’ll ask Ken to get in touch with you later today. Will you be at this number?
M: Yeah, till four... Look, I’ve got to go. I have to get all the orders out before I leave today.
W: OK, thanks, Tim. Bye.
19. Where does Tim work?
20.Why does Ruth call Tim?
21.What does Tim offer to do?
22.When can Ken get in touch with Tim at the same number?