阅读下面的短文，从短文后的选项中选出能填入空白处的最佳选项补全短文。选项中有一项为多余选项。
| A. skilled kids may forget green hands B. so an adult should always be present C. But swimming can also be dangerous D. a few seconds can make a big difference E. Or you could hit your head on the bottom |
Summer is here. One of the best ways to cool off on a hot summer day is to jump into a swimming pool. Swimming is great exercise, and a trip to a pool or beach is a good way to have fun with friends. , so it's important to stay safe as you do it. Here are a few things you can do to swim safely.
●Swim only in areas set for swimming.
Don't swim unless there is a lifeguard (救生员) on duty. If you're on a beach near the ocean, this is especially important. In some places, fast currents (急流) can sweep swimmers away without warning. So if a sign says "no swimming", please take care.
Be careful when diving (跳水) into the water headfirst.
Most pools have deep ends where diving is safe. In natural water, don't dive unless you know that the water is deep enough. , causing injury (伤害) or death.
●Make sure you have a partner with you.
Nobody knows what will happen while you are swimming. If something goes wrong, you can get help from that person as soon as possible. In this situation, .
●Pay close attention to children's safety.
Kids who don't know how to swim should wear life jackets. But by themselves they are not enough, . If you have a pool at home, put a fence (围栏) around it in case children fall in. And if a child disappears, check the pool first.
