In my opinion sport is important for healthy free time. Sport also makes people strong and prepares a lot of joy.
Some people participate in sports, others prefer watching them on TV. It is known that walking for an hour is healthier than irregular participation in any active physical activities. To keep fit some people join special classes or take part in aerobics or yoga, do some kind of training in a gym. Others play football, badminton, volleyball, tennis.
Children of your age have to eat more food.
If you want know english better, you should spend more time warking with your dictionary.
They should learn the rules of using the library.
Students should return themselfs(возвращаться)/return books(возвращать книжки) to the library in time. (Вообще-то, "in time" это вовремя, но как переводится "належний час" я не знаю.)
We should work hard if we want have time to watch the concert.
He should not ride a bike in (или "at") the street, where is heavy traffic.
You should not use dictionaries during your examination of tests.