Do teenagers in small villages do chores at home? How about the teenagers in big cities? Here is a survey. We asked 4,000 teenagers in China several questions. Half of them come from big cities like Beijing, Shanghai and Guangzhou. The others are from small villages. We made a diagram of the result of our survey. Let's have a look at it. We found out that teenagers from small villages do more chores than those from big cities. Maybe it is because they live a harder life. Our advice to parents in big cities is that parents should give their children some chores to do. Doing chores teaches teenagers to take care of themselves.

    Chores 2000 teenagers in small villages.

    Chores 2000 teenagers in big cities

上体育课时，体育老师发现同学们要用的篮球差气，于是他用打气筒给篮球打气，当篮球变圆后，仍继续给它打气，则篮球内气体的质量、体积、密度的变化过程是（   ）

下列海域中，属于我国内海的是

①将三合板或硬纸做成直径约30cm的圆板．圆板的中心有一孔，可以套在转台的转轴上，用螺丝夹紧后，由皮带传动绕轴转动．圆板的正面按图所示的顺序和比例贴上七种颜色的蜡光纸．

②实验时，光照在彩色的蜡光纸上，可以看清圆盘上的七种颜色．转动圆板，七色盘的转速足够大时，板面呈现白色．这是由于人眼的视觉暂留现象，在视网膜上七种颜色的光叠加，引起白色的视觉．

问题：

恩格斯曾对1871年德意志帝国宪法作过这样的评述：“在资产阶级借以组织其统治的国家机构中，也有许多东西是工人阶级可能利用来对这些机构本身作斗争的……资产阶级和政府害怕工人政党的合法活动更甚于害怕它的不合法活动，害怕选举成就更甚于害怕起义成就。”恩格斯的评述主要说明(     )