题目

Many facts suggest that children are overweight and the situation is getting worse, according to the doctors. 【1】.Some people blame the fact that we are surrounded by shops selling unhealthy, fatty foods, such as fried chicken and ice cream at low prices. 【2】, then probably children would buy less take-away food.【3】. I agree with this, because good eating habits begin early in life, long before children start to visit fast food shops. If parents often give their children fried chicken and chocolate rather than healthy food, they will go for sweet and salty foods, and children will 15．只列式不计算．一根绳子长3米，第一次用了全长的$\frac{2}{13}$，第二次用了全长的$\frac{5}{13}$．①两次共用了全长的几分之几？算式：$\frac{2}{13}$+$\frac{5}{13}$②还剩下全长的几分之几？算式：1-（$\frac{2}{13}$+$\frac{5}{13}$）．