second order theory

例句：

1. 1. The second-order theory of economics is a complex field that has been studied for decades.
   经济学的第二阶理论是一个复杂的领域，已经研究了几十年。
2. 2. In the second-order theory of quantum mechanics, particles can exist in multiple states simultaneously.
   在量子力学的第二阶理论中，粒子可以同时存在于多个状态。
3. 3. The second-order theory of learning suggests that memory is not just about encoding information but also about retrieving it later.
   学习第二阶理论认为记忆不仅仅是关于编码信息，还包括后来检索信息的过程。