英语语法分析

The approach of Epidemical Field Research was applied.

采用现场流行病学调查方法。

Methods:We adopted Epidemical Field Investigation method to study it.

方法：采用流行病学现场调查方法。

In this paper, a discrete stage-structured epidemical model is proposed and studied.

本文主要讨论了离散的阶段结构传染病模型。