In the morning, there are three little brothers playing football on the lawn in the park. At this time, a little sister comes here. She says to the three little brothers, don't play football on the lawn. If you step on the grass and it hurts, the grass will be very sad. We should take good care of the lawn. The three little brothers bowed their heads and said to the little sister, "we will not play football on the lawn in the future.".