We shall not drown (淹死) if we remember these rules: 1, Never swim alone. 2, Never swim at a beach if there is no lifeguard (救生员) . 3, Never swim after a meal or when you feel hungry or tired. 4, Never depend on rings, floats (漂浮物) or other swimming aids (助) . You may lose them or they may let you sink (下沉) . 5, Don ’ t stay in the water too long ,especially if it is cold. 6, Before you dive, be sure the water is deep enough and you will not hit anybody. 7, Never go out in a boat if you can not swim or if you are not wearing a life jacket. If you get into difficulty, this is what you should do : 1, Keep calm (镇定) . Save you strength and your breath. 2, Try to float on your back or tread (踩水) water. To tread water, move your feet as if you are climbing some stairs. 3, Raise your right arm for help. Remember : a red flag means that it is dangerous for all swimmers to enter the water. A blue flag means that it is dangerous for children and weak swimmers to enter the water.