doctrine of collaboration between labour and capital

例句：

1. 1. The scientist developed a new theory to explain the phenomenon.
   科学家提出了一种新的理论来解释这一现象。
2. 2. The philosopher believed in the importance of individual freedom.
   哲学家相信个人自由的重要性。
3. 3. The teacher explained the concept of gravity to her students.
   老师向学生们解释了重力的概念。