A、They become lighter when the temperature is low. B、Their chemical composition changes with the temperature. C、Their color dark

M: It’s so cold now, but this morning it was so hot and sunny. I wish there was a way I could always be wearing the most suitable clothes for the temperature.
W: I recently read that in ten years we’ll be wearing clothes that change with the weather. So when it’s cold, our clothes will warm up, and when it’s hot. our clothes will cool off.
M:(13)Oh, very funny! So we’ll be wearing gigantic clothes with built-in air conditioners and heaters.
W: I’m being serious!(14)Researchers have discovered a method of treating fibers with plastic crystals capable of storing and releasing heat as the temperature fluctuates. These treated fibers absorb more heat than untreated fibers. Researchers are still working with this, but soon this process will be widespread.
M: That’s fascinating. I didn’t know that fibers had the capability of storing heat. How does that work?
W:(15)These fibers work with the heat by rearranging their structures. The treated fibers move back and forth between two solid shapes.
M: I don’t understand. What kind of shapes do they change into?
W: When the weather gets cooler, the crystals become cooler and revert back to their original structure.
M: That’s truly unbelievable. You said that it’ll be a decade before this type of clothes will be available. What a shame! I don’t think I can wait that long.
13. What is the man’s initial reaction to what the woman describes?
14. What is unusual about the fibers treated with special plastic crystals?
15. How do the fibers work as the temperature changes?