根据短文内容，用括号内所给单词的正确形式填空。
Swimming is very popular in summer. People like swimming in summer because water (1) ________
(make) people feel cool. If you like swimming and swim in a wrong place, it may not be safe. Last summer,
more than ten people died while they (2) ________ (enjoy) themselves in the water, and (3) ________ (many)
of them were students. But some people are still not careful in swimming. They often think they swim so well
that nothing can happen to them in water. Summer is here again. If you go swimming in summer, don't forget
that better (4) ________ (swim) have died in water. They died only because they were not careful, not
because they could not swim. So don't get into water when you go swimming yourself, go with your teachers
or your parents. If there are"No swimming" signs, don't get into water, either. If you remember these,
swimming will be (5) _______ (safe).
