A、Keeping out the cold. B、Keeping out the heat. C、Avoiding air pollution. D、Preventing the dust. A男士说房子经常用纸来防御寒冷，接着又说了几个例子表明纸可以御

M: Last time we talked about the history of paper, but do you know what paper is used for?
W: Oh, that’s an easy question. Paper is used for newspapers, books, writing paper, envelopes, wrapping paper, paper bags...
M: Yes, actually only half of the paper that is made is used for such purposes. Have you got an idea about other uses of paper?
W: No, I’m afraid not.
M: There are many other uses. Paper is very good for keeping you warm. Houses are often prevented against cold by paper. You have perhaps seen homeless people asleep on a large number of newspapers.
W: Yes, I have. So they are preventing themselves against cold.
M: You are right. In Finland, it is very cold in winter. It is sometimes 40 degrees Centigrade below zero. The farmers wear paper boots in the snow. Nothing could be warmer.
W: Oh, that’s unbelievable.
M: Now more and more things are made of paper. We have had paper plates, cups and dishes for a long time. But now we hear that chairs, tables, and even beds can be made of paper.
W: Amazing!
M: People have made paper boats, but they have not yet made paper planes or cars. Just wait, they probably will.
W: Well, you have become an expert on paper. How do you know all that?
M: You know, I’m preparing for a presentation on paper, so I’ve looked up a lot of material.
W: Well, I’m sure your presentation will go really well.
M: Thank you.
22. What function does paper perform in house-building?
23. Why do farmers of Finland wear paper boots in winter?
24. What do we learn about paper planes and cars?
25. How has the man got to know so much about paper?