每个捐助者都要利用社会上层人士以确保自身项目的成功，惟恐被别人占先。

Each donor exploits the best people to ensure the success of its own projects, lest another donor exploit them first.

建立了占先结构类可以由条件断言(正)布尔组合刻画的充要条件以及有限刻画的充要条件。

We have established the characterization for the classes of preferential structure can be expressed or limited expressed based on Boolean combinations of conditional assertions.