如图为洋葱鳞片叶内表皮细胞临时装片制作过程，请根据所学的知识判断下列说法是否正确．

    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

下列有关生物膜的说法正确的是(　　)

①犯罪是侵害社会健康肌体的毒瘤

②惩罚犯罪行为就必须判处死刑

③犯罪对自己、他人和社会危害严重

④只有犯罪才具有社会危害性