英语语法分析

To locate an extremum we look for these points.

为了确定极值，我们需要找这些点。

The note gives an extension of extremum principle for harmonic functions.

本文给出调和函数极值原理的一种推广。

It has revealed the relations of every extremum principle each other in certain extent.

这在一定程度上揭示了各极值原理间的相互关系。