题目

细胞膜的作用是（ ） A . 保护 B . 支持 C . 控制物质进出 D . 保护和控制物质进出 答案：D America is grooving older. Fify years ago, only 4 out of every 100 people in the United Satates were 65 or older. Today, 10 out of every 100 Americans are over 65. The aging of the population will affect American society in many ways - education, medicine, and business. Quietly, the graying of America has made us a very different society-one in which people have a quite different idea of what kind of behavior(行为) is suitable at various ages. A person’s age no longer tells you anything about his/her social position, marriage or health. There’s no longer a particular year in which one goes to school or goes to work or gets married or starts a family. The social clock that kept us on time tells ads it used to be. It doesn’t surprise us to hear of a 29 -year-old man who has become a father for the first time. Public ideas are changing. Many people say, “I’m much younger than my mother or my father was at my age.” No one says “act your Age” anymore. We’ve stopped looking with surprise at older people who act in youthful ways. 72. It can be learnt from the text that the aging of the population in America _____. A. has made people feel younger B. has changed people’s social position C. has changed people’s understanding of age D. has slowed down the country’s social development 73. The underlined word “one” refers to_______ . A. a society  B.America  C.a place  D. population 74. “Act your age” means people should ____ . A. be active when they are old B. do the right thing at the right age C. show respect for their parents young or old D. take more physical exercise suitable to their age 75. If a 25-year-old man becomes general manager of a big firm the writer of the text would most probably consider it _________. A. normal           B. wonderful        C. unbelievable       D. unreasonable