阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

    Summer is coming. The weather becomes hotter and hotter. A lot of people like swimming in the swimming pools or in the sea. They think water makes them (feel)cool. But some people are not careful enough. They often think they can swim (good) than others and they don't have to worry about anything. So these years, many accidents happened and some people (lose) their lives. Most of them were students. As we all know, (safe) is the most important. Do you know  to protect yourself?(protect)yourself, you must be careful. Remember not to swim in a (danger) place. Don't swim alone, and  you see a "No Swimming" sign, don't swim, either. Of course, you can swim  someone who can keep you safe. If you remember these, swimming(be)safer.