People with a sense of fulfillment think it a good world and would like to conserve it as it is, while the frustrated favor radical change.

我们必须从一开始就考虑产品的生命周期终结问题。

丙型肝炎病毒是一个隐藏的敌人，但只要拥有正确的工具和决心，任何隐藏的敌人都能被发现。