抽象類：
In some countries, young people are not only richer but also safer and healthier than ever before. However, they are less happy. What do you think are the causes of this? What solutions can you suggest? 在一些國家，年輕人更加富有，安全，健康，但是，他們還是不快樂，原因何在，怎樣解決?
In some countries, young people are not only richer but also safer and healthier than ever before. However, they are less happy. What do you think are the causes of this? What solutions can you suggest? 在一些國家，年輕人更加富有，安全，健康，但是，他們還是不快樂，原因何在，怎樣解決?