A、When he is travelling around. B、When he is doing research work. C、When he wants to get portraits shots. D、When he takes pictur

W; I like that picture you put up on the wall.
M: Oh, thank you. It’ s a photograph that I took on my vacation last year.
W: You took it yourself? I didn’t know you were a photographer.
M: Oh, yes, I’ve been taking pictures for years.
W: It sounds like an interesting hobby. Do you have any more of your pictures here?
M: I have some that I haven’t enlarged.
W: May I see them?
M; Yes, certainly. I haven’t really sorted them out yet. Some of them are faces, just faces of people whom I see when I’m walking around
W: Do you let them know that you’re taking pictures of them?
M: I try not to. I don’t like pictures of people who pose for the camera. I like people who are going about their daily business without being aware of the camera.
W: And what are the rest of the pictures?
M: A few of them are landscapes, and the rest of them are still-life studies that I took in my studio.
W: Oh, you have your own studio! But I suppose you need a lot of equipment. How many cameras do you have?
M; Well, I have several, but I use two of them more than the others. Here, this is the one that I use to get the portrait shots.
W: What’s your other favorite?
M: It’s the one I use for the pictures that I take in my studio. It’s too big to carry around.
W; When are you going to take a picture of me?
M: Sometime when you don’t know that I am taking one.
Question No. 19 What picture did the man put on the wall?
Question No. 20 How does the man take pictures of people when he’s walking around?
Question No. 21 According to the man, when does he use the bigger camera?
Question No. 22 What kind of pictures has the man NOT taken yet?