【正确答案】 Experts say that quite a number of people who are 18 to 45 years old are under sub-health condition. They are not suffering from obvious diseases but their physical functions are in a weak state.
Why are these people, who are in their golden ages, in sub-health condition? First, people aged between 18 and 45 are so busy with their study or work that they can't spare enough time for physical exercise. Second, air pollution and water pollution affect our lives so badly that we could hardly maintain a good health.
In order to get rid of sub-health, it is of great importance that we do outdoor exercise frequently to remove weariness and have our body refreshed. Besides, governments should try harder to protect the environment so that people have fresher air to breathe and cleaner water to drink.

【答案解析】本文是一篇议论文，讨论亚健康的问题，文章内容安排如下：
第一段简述问题。
第二段分析原因。
第三段提出个人建议。