1、
Chapter one discusses the basic theory of the principle of change of circumstances.
本文共分四章：第一章情事变更原则的基本理论。
互联网
2、
Basic position of the theory base of the principle of change of circumstances.
关于情事变更原则理论基础的基本定位。
互联网
3、
The basic structure and working principle of biomimetic fish fin is briefly introduced.
摘要简要介绍了仿生鱼鳍的基本机构和工作原理.
互联网
