Last year, some groups of students in their community (社区) made a survey about “How do people spend their free time? ” The following diagrams(图表) show some results of it:
    Diagram (1): Hours for people of different ages who surf the Internet in a week.

    Diagram (2): Different days people go to the library. (library attendance)

    Diagram (3): Different programs people like.

穆罕默德·阿里对埃及的近代化作出的最重要的贡献是(     )

假如一做圆周运动的人造卫星的轨道半径r增为原来的2倍，则（   ）