A、Booking a theatre ticket. B、Reserving a room. C、Booking an air ticket. D、Reserving a seat. C根据文中开头提示信息“Will you book a plane t

M：Good morning. Will you book a plane ticket to London for me?
W：Yes, sir. What time would you like to leave?
M：Next Tuesday, if possible.
W：That’ll be the 21st of December.
M：Yes, that’s right.
W：There are several flights available.
M：Would you check what flights are available on the 21st of December?
W：All right. Let me check it over.
M：Morning flights will be perfect.
W：Yes, sir. There is a flight available on that day, at 10:00 a.m.
M：Fine. I’ll take that flight, then.
W：10:00 a.m. I’ll fix your ticket.
M：When do I check in?
W：You must be there by 9:00 a.m.
M：Thank you.
Q18：What does the conversation talk about?
Q19：What’s the relationship between the two speakers?