A、At the airport. B、At the post office. C、At the bookstore. D、At the travel agency. B 对话涉及的是寄一封航空信到多伦多的邮费。根据对话的内容判断，谈话的地点应当是邮局。

M: How do you get to the park for exercises every day, Grandma?
W: Well, it’s within walking distance, but I usually take the bus since the bus stop is just in front of our house.
Q: How does the old woman get to the park on most occasions?

M: Approximately how long does it take for a letter to go by air mail from here to Toronto?
W: Three days. An airmail letter from here to Toronto should not take more than three days.
Q: Where does this conversation most probably take place?