阅读理解 The greatest contribution to civilization in the century may well be the air-conditioning- and American leads just as amazing is the speed with which this situation came to be. Air-conditioning began to spread in industries as a production aid during World War II. Today most Americans need to take air-conditioning for granted to homes, offices, factories, theatres, shops, studios, schools, hotels, and restaurants.
But not everybody is aware that high cost and easy comfort are merely two of the effects of the vast cooling of American. In fact, air conditioning has substantially altered the country' s character and customs.
Many of the byproducts are so conspicuous that they are scarcely noticed. To begin with, air-conditioning transformed the face of America by making possible those glassy, boxy, sealed-in skyscrapers. It has been indispensable, no less, to the functioning of sensitive advanced computers, whose high operating temperatures require that they be constantly cooled.
It has, at will, forced families into retreating into families with closed doors and shut windows, reducing the interactions of neighborhood life. It is really surprising that the public ' s often noted withdrawal into self-pursuit and privacy has coincided with the historic spread of air-conditioning. Though science has little studied how habitual air-conditioning affects mind and body, some medical experts suggest that, like other technical avoidance of natural variations in climate, air-conditioning may damage the human capacity to adapt to stress. If so, air-conditioning is only like many other greatly useful technical developments that liberate man from nature by increasing his productivity and power in some way - while indirectly weakening him in others.