A、To give an example of a bad reaction to penicillin. B、To show how penicillin has changed over the years. C、To emphasize the im

W: So how are you feeling?
M: Much better now that I began taking an antibiotic. Student health gave me one, and it’s really help. You know what amazes me is that the human races 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. Tetracycline works that way.
M: Wow, you are a fund of drug trivia. How do you know all these?
W: My mother used to look up all our medicines, prescription and non-prescription. There are lots of books around. It’s interesting. What antibiotic 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 lab tomorrow.
Questions 16-20 are based on the conversation you have just heard.
16. What are the speakers mainly discussing?
17. What caused her father almost to die in the 1940’s?
18. Why does the woman tell the story about her father?
19. Where did the woman learn about antibiotics?
20. What will the man probably do next?