听力原文：W: Hi, Rob, you know that class you missed yesterday? M: Yes, but I was seriously iii. W: I'm sorry to hear that. You (:an have my notes. M: Thanks. I appreciate that. W: So how are you feeling? M: Much better now that I began taking an antibiotic. Doctor Lee gave me one, and it really helps. You know what amazes me is that how the human beings managed to survive before antibiotics. W: I agree. When my father was a young boy in the 1940's, he got blood poisoning and would have died. But his doctor had heard of this new drug called penicillin. M: Wow, he was really lucky. And now we have lots of antibiotics that kill bacteria. W: Well, penicillin kills bacteria, but not all antibiotics do. Some are just slowing the bacteria down until our normal immune defenses can finish the job. M: Wow! How do you know all these? W: My mother used to look up all our medicines. There are lots of books around. It's interesting. What antibiotics are you taking? M: I don't remember. It's on the bottle. I think I'll take a new look at the label and drop by the library to see if they have reference books on medicines. See you in the lab tomorrow. (23)