The population of the United States is growing older and will continue to do so.

According to a report, 39 million Americans will be 65 or older by the yew 2010, 51 million by 2020, and 65 million by 2030.

   The "graying" of the United States is mainly due to the fact that people in the U. S. living longer. As a matter of fact, the number of U.S. citizens 85 years old and older is growing six times as fast as the rest of the population. It is also largely due to the old-growing of the "baby boomers," the generation born after World War II. In 1957, over 4.3 million babies were born. More than 75 million Americans were born between 1946 and 1964, the largest generation in U.S. history. In less than twenty pears, millions of them will become elderly people.

   The "graying" of the U.S. will greatly affect the nation's family and workforce. One likely development will be a gradual change in the family unit; it will move away from the nuclear family and towards a multigenerational family. The other likely development will be a change m the proportion (比例) of the nation's workforce. In 1989 there were 3.5 workers for every person 65 and older; by the year 2030, there will only be 2 workers for every person 65 and older.

 

 

Title  76. Graying USA_

Numbers of citizens 65 or older

77.          

By 2020

By 2030

39 million

51 million

65 million

78. Causes/reasons

79.                  

Baby boomers’ old growing

80. Effects/Results

81.  

83.             

-- multigenerational family

82.              

                

84.         to citizens 65 or older

85.         

By 2030

3.5:1

2:1

    At Dallas/Fort Worth Airport, the lights are controlled by sensors that measure sunlight. They dim immediately when it's sunny and brighten when a passing cloud blocks the sun.

   A wall of windows at a University of Pennsylvania engineering budding has built-in blinds (百页窗) controlled by a computer program that follows the sun's path.

   Buildings are getting smarter -- and the next generation of building materials

expected to do even more.

   Windows could catch the sun's energy to heat water. Sensors that measure the carbon

dioxide breathed out by people in a mom could determine whether the air conditioning needs to be turned up.

   Many new materials and technology have been designed in the last 15 years. They now being used in a wave of buildings designed to save as much energy as possible. They include old ideas, like "green roofs," where a belt of plants on a roof helps the building keep heat in winter and stay cool in summer, and new ideas, like special coating for windows that lets light in, but keeps heat out.

   As technologies such as sensors become cheaper, their uses spread.

   The elevators (电梯) at Seven World Trade Center, which is under construction in New York, use a system that groups people traveling to nearby floor into the same elevator, thus saving elevator stops. People who work in the building will enter it by swiping (刷) ID cards that will tell the elevators their floor; readouts will then tell them which elevator to use. The building also has windows with a coating that blocks heal while letting in light.

   More new building materials and technology are in development. A Philadelphia building farm is now working on "smart wrap" that uses tiny solar collectors to catch the

sun's energy and transmitters (传感器) the width of a human hair to move it. They are expected to change the face of the construction industry in the next ten years or so.

72. __ will be developed and used in the construction industry.

     A. "Green mops" that cool or heat buildings

     B. "Smart wrap" that catches the sun's energy

     C. Sunlight-measuring sensors that control lights

     D. Window coating that lets light in, but keeps heat out                          

73. The elevators at Seven World Trade Center are special because they can ___

     A. send people to floors with fewer stops

     B. teach people how to use their ID cards

     C. make people stay very cool in summer

     D. help people go traveling in the building                                                

74. The underlined word "it' in the last paragraph refers to _____.

     A. a human being            B. smart wrap

     C. the sun's energy                 D. a transmitter                   

75. What might be the most suitable title for the text?

     A. Buildings Are Becoming Smarter

     B. Buildings Are Getting More Sunlight

     C. Buildings Are Lacking in Much Energy

     D. Buildings Are Using Cheaper Materials              
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