单项选择题
听下面一段对话，回答下列问题。
17-20
W: Good morning, everybody. Today for our writing class, we are glad to have Mr Henry Stone with us. A well-known writer in this country, he is going to share with us his writing experiences. Now, Henry, please tell us how you find so many interesting things for your stories.
M: OK, I watch people a lot, I do that when I travel, I have been to many countries such as Britain, Italy, and Sweden. So I spent a lot of time at the airports, while waiting for my flights, I watch people passing by and start my imagination. For example, the other day when I was waiting for my flight to Greece, I saw a couple, they were buying magazines at that moment, they were not wearing business clothes, but the man was carrying a suitcase, every few seconds, the woman looked around, I wondered someone was following them. Perhaps they were running away and, you know, this reminded me of a story in the newspaper that day: A banker stole one million ponds a week before and disappeared with his wife, there was a picture of them in the paper, the couple really looked like the thieves, maybe I should stop them. Just then, I saw them say goodbye to each other. And the woman walked away. Well, sometimes I make mistakes like that, but I find things like that very useful for my writing.
A. Reading.
B. Writing.
C. Listening.
D. Speaking.