How to keep healthy

    Everyone wants to be healthy,but do you know how to keep healthy? First, eating right food is very important. There is a lot of healthy food. It can make you strong. You can have more bananas,apples,tomatoes,cucumbers and so on, because fruits and vegetable are good for you.But you should not eat too much chocolate or fast food.They're not healthy food.Second,sports can also keep you healthy.Get up early and do some sports every day.You will be healthy and happy by doing so.

董诚,一位普通职工,几十年如一日,坚守“把有限的生命投入到无限的为人民服务中去”的信念,被群众亲切地称为“咱身边的活雷锋”。他耸起“雷锋110”灯塔照亮人们的心灵。他的事迹说明(　　)

①不计较代价与回报的奉献精神,是社会责任感的集中表现

②助人为乐、服务社会,是我们义不容辞的法定义务

③热心公益,在奉献中提升自身的价值

④参与社会公益活动,有利于营造“我为人人,人人为我”的社会氛围

小玉漫步在雪后海边，发现道路上的水都结了冰，但海水却没有结冰的．她想到水的凝固点是否与水中含盐量的多少有关呢？于是，她设计了如下探究实验过程，请你和她一起完成这个实验过程．

密西西比河水流平稳，利于航行，主要原因是（   ）