“Early to bed, early to rise（起身）makes people healthy, wealthy and wise（健康，富有，聪明）.” This is an old English saying. Children should have ten hours' sleep every night, or they can't do their work very well. They will not be wise. The body needs exercise. Walking, running, swimming and playing ball games are all exercise. Exercise keeps the body strong.

七年级（3）班的小红同学觉得自己不是小孩子了，很多事情不喜欢爸妈干涉，可碰上“大麻烦”又渴望爸妈的帮助；喜欢在同学面前表现自己，又怕别人说三道四；总觉得长大了，可还是经常做傻事。

分子模型可以直观的表示分子的微观结构（分子模型中，不同颜色、大小的小球代表不同的原子）。右图所示的分子模型表示的分子是（   ）