阅读下面短文，掌握其大意，然后从各题所给的A、B、C和D项中，选出最佳选项。
When the weather turns warm, everyone wants to be in or around the water. Hanging out at the pool or the beach on a hot day is a great way to beat the heat.
Most people don't think much about water 1—but they should. For people between the ages of 5 and 24, drowning is the second 2 cause of accidental death.
It doesn't have to be that way, 3.By knowing how to stay safe and following a few simple guidelines, most water related accidents can be 4.
It's a good idea to swim only in places that are watched over by a lifeguard. 5 can predict changing ocean currents, sudden storms, or other 6 dangers. In the event that something does go wrong, lifeguards are trained in 7 techniques.
Swimming in an 8 body of water(like a river, lake, or ocean) is different from swimming in a pool. You need more 9 to handle the currents and other changing conditions in the open water.
If you do find yourself 10 in a current, don't panic and don't fight the current. Try to swim parallel(平行) to the shore until you are able to 11 the current, which is usually a narrow channel of water. 12 try to make your way back to shore as you do so. If you're 13 to swim away from the current, stay calm and 14 with the current. The current will usually 15，then you can swim to shore.
16 a very good swimmer who tries to swim against a strong current will get worn out. If you're going to 17 in open water, better take lessons that provide you with tips on 18 unexpected dangers.
Some areas with extremely strong currents are 19 limits when it comes to swimming. Do your research so you know 20 not to swim, and pay attention to any warning signs posted in the area.
