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.

生活中，人们常常把碗放在锅内的水中蒸食物，要求是碗不能与锅底接触，当锅里的水沸腾时，碗里的水会              （   ）

人体呼吸道表面的黏膜和纤毛都有阻挡病原体进入人体的作用．