помогите пожалуйста сделать 1,3,4 упражнения

№ 11. you must be a good swimmer to go water sking.2. you mustn't drop litter in the street.3. you don't have to be old to enjoy gardening.4. you mustn't walk alone in cities.5. you have to be quiet in the contryside№ 31. be careful2. to break rules3. be quiet4. to do my homework5. will rest