Can you swim? Swimming is one of the most popular activities in summer. It can be learned early in life. Little children can learn to swim as soon as they walk. In fact, you need the same skills in walking as in swimming. However, I believe that five is the best age to learn it. By five or six, a child knows fear of water, a very important thing to know. It's wise to be afraid. The young understand that the water can sometimes be very dangerous. When you swim, you should follow certain rules: Never swim alone! No matter how good you are in the water, don't risk drowning by swimming alone. If you swim by yourself, you may get into trouble. Don't go beyond your abilities. Most swimmers know it clearly not to swim too far from the bank or the beach. Don't show off your skills by doing dangerous tricks. Don't smoke. Swimming depends on a healthy body. Work at any activity that builds muscles  . According to the passage, you should not swim alone because  _  .
the water is too cold your parents would not be happy something in the water might attack you might drown