A、He had thought Chicago was a young city. B、He had thought that Chicago was very large. C、He had thought that Chicago should be

W: Hey, Mike! Did you attend Mr. Johnson’s seminar on the History of Chicago?
M: Yes, I did. I didn’t notice you were there, too.
W: I was late for it. Wasn’t it a great seminar? I have learned so much!
M: It certainly was. I hadn’t understood that Chicago was such a young city, less than 200 years old
W: Yes, I thought it was an old city before, but it turned out that I was wrong. You still remember what Mr. Johnson said? The army fort, Fort Dearborn, was built in 1803 in the place that would become Chicago. Chicago didn’t officially become a town until 30 years later, in 1833.
M: Yes. and when it officially became a town in 1833, it was very small. It had a population of only 350. Think about that, only 350 people! It was really a tiny town by then.
W: But it’s a pity that after Chicago had grown, much of it was destroyed in a fire. Just imagine! What a big fire it was!
M: The Great Chicago Fire was in 1871. Chicago wasn’t even forty years old at the time, but it had grown much bigger.
W: Yet only twenty-two years later, in 1893, Chicago was able to host a World’s Fair. It was such a huge development for a city.
M: Yes. Chicago had been rebuilt after the fire and was eager to show itself off to the rest of the world at the World’s Fair in 1893.
W: I will attend another seminar on the Economy of Chicago next week. Mr. Johnson will talk about the economy specifically. Will you be there too?
M: Yes. so I will see you next Thursday.
19. What had the man thought about Chicago before he attended the seminar?
20. What do we learn from the conversation about Chicago?
21. What do we learn about the Great Chicago Fire from the conversation?
22. What will the two speakers do next week?