经济理论为理解市场原则提供了一个框架。

Economic ___theory provides a framework for understanding market principles.

经过广泛研究，博弈论在战略规划中的应用才变得明显。

Only after extensive study did the applications of game ___theory become evident in strategic planning.

量子力学的基础理论基于复杂的数学原则。

The ___theory underlying quantum mechanics is based on complex mathematical principles.