公共卫生服务是一种成本低、效果好的服务，同时也是一种社会效益回报周期相对较长的服务。
Public health service is not only a low -cost and effective service, but also a service with a relatively long-time social benefit return.
它可以比较粗略地描述成是发生在固定周期（这个周期通常是一年一次）的包含某一个物种很多成员的集体旅行，并且只有在长途旅行后才有回报。
It can loosely be described as travel that takes place at regular intervals—often in an annual cycle—that may involve many members of a species, and is rewarded only after a long journey.
在信用周期的积极阶段，超额回报首先产生于对信用升级的正确预测，以及在消极阶段首先产生于对信用降级的正确预测。
In positive phases of the credit cycle, alpha is generated primarily from the correct forecasting of upgrades, and in negative phases primarily from correctly forecasting downgrades.
应用推荐