【英语时差8,16】烘干机如何工作（上）（在线收听）

Throw your laundry into the dryer without a dryer sheet, and it comes out a rumpled, “staticy” mess. Toss one in and the results are much better. How can adding this flimsy sheet change the way all your clothes come out of the dryer? When you first add a dryer sheet to your wet laundry, it does nothing at all. It only starts working when the dryer is on. The warm air that circulates through the damp clothing releases chemicals from the dryer sheet, and these chemicals permeate all the clothing, even clothing the dryer sheet never directly touches. The chemical that a dryer sheet releases is known as a “surfactant.” Most surfactant molecules have two sides: one that holds onto water, and one that holds onto fats and oils.