首先

But at the same time, the development of economy is at a cost of the destruction of environment.

首先，世界范围内生态环境的不断恶化是技术性贸易壁垒持续发展的主要原因。20世纪以来，随着工业的高速发展和科学技术的进步，世界各国经济都不同程度的在原有基础上实现了很大的增长，同时人们的生活水平也得到和大幅度的提高，这是值得肯定的。

First, they must be one of the best at their position.

首先，他们必须是一个最好的，在他们的立场。

At first, I thought it difficult for me to sing this song

首先，我觉得唱这首歌对我来说有点难。

At first,I have something important to tell you.

首先，我告诉你们有一些重要的事情。

At first, English is very important for me.

首先，英语是非常重要的我。

At first, it was a very hard thing for me.

首先，这是一个非常困难的事情。

At first, this is going to be a challenge, but it will get easier with time.

首先，这将是一个挑战，但它会更容易随着时间的推移。

First, I asked him what was at risk.

首先，我问他什么是风险。

First of all, granularity of the tests is at the level of outputs of the system.

首先，在测试粒度在本系统的产出水平。

At the outset, I want to thank you for your kindness to me

首先，我要感谢您对我的友爱和问候。

The work of this paper is as follows: 1. Looking back the progressing history of the linear motor, introducing the features of the elevator driven by linear induction motor, radicating the topic of this paper "the digital frequency variable control of the elevator bi-side direct driven by linear induction motor". The research of this paper covers the conventional VVVF control, space vector based VVVF control, vector control and DTC.

本文主要开展了以下几个方面的工作： 1 回顾了直线电机发展历史，电机的驱动技术演变，特别是针对直线电机的驱动，简要介绍了直线感应电机驱动电梯的优点和不同结构类型，对传统的v／f控制，基于空间矢量法的v／f控制，矢量控制，和基于电压空间矢量的直接转矩控制进行了比较，确立了本课题的研究主题：直线感应电机双边直推式驱动电梯的全数字变频控制。

The article combines with the treatment of a superficial civil air defense work to introduce how the grouting method to improve the performance of the backfill soil.

文章从治理漂浮人防工事的角度提出了注浆技术在改善回填土性质方面的应用，并详细阐述了注浆技术的施工流程。