essentiality

例句：

1. 1.The essence of the problem lies in its complexity.
   问题的本质在于其复杂性。
2. 2. The fundamental principle of this experiment is to test the theory.
   这个实验的基本原理是测试理论。
3. 3.The importance of education cannot be overstated.
   教育的重要性无法被低估。