首先

Influences of the nature of the electrodes, the workingpotentiasl, the passed charge and the concentration of acetophenone on theelectrocarboxylation have been studied.

首先运用循环伏安法研究了苯乙酮的电还原行为。

First, the surface treatment on the graphite and acetylene black was carried out as following.

本文首先对导电剂石墨和乙炔黑进行了表面处理。

Therefore, we should first make sure that our goals are clearly defined and achievable.

因此，我们应该首先确定我们目标明确且可以完成。

Many moral rationalists believe that moral reasoning is based on practical reason, which involves choices about what to do or intend to do, including how to achieve one's goals and what goals one should have in the first place.

许多人的道德理性主义认为，道德推理是实际的理由，涉及约做什么或打算，包括如何实现自己的目标，什么目标之一应该首先选择方案。

First, you click your preferred primary color. From there, you choose your preferred secondary and achromatic colors.

首先，点选你最喜欢的主色，之後，再选择你喜欢的次要颜色，还有消色差的颜色。

First, the speed of the reaction between mud acid and rock is very fast, the effective distance of acid is short, active acid can not reach deep formation.

首先，高温下常规土酸与地层矿物反应速度极快，酸液有效作用距离短，活性酸不能到达地层深部；其次，HF与铝硅酸盐的化学反应不是简单的一次反应，其副产物氟硅酸和氟铝化物还可与铝硅酸盐发生二次反应和三次反应，形成一系列不溶性的沉淀物，对储层造成严重伤害；第三，高温情况下酸液对井下管柱及工具腐蚀性很强，对缓蚀剂性能要求高。

In chapter 2, we first introduce the physical and chemical properties of amino acids.

第二章首先简要介绍了氨基酸的物理和化学性质。

First, the definition, significance, research emphases and status of NC machining verification technology are introduced in this paper. Then the platform—ACIS for the development of verification system, including its development interface, data structure, main functions, features and the application in the system is introduced. And, we indicate in brief the correlative knowledge of NC machining and then discuss the definition of the machining environment of NC machining verification system as well as the way that the module has been developed. Finally, we describe how to make Help Files and the structure of the Help Files in the system.

本文首先对数控加工动态仿真技术的定义、意义、研究重点、研究状况进行了介绍；并介绍了可用于开发数控仿真系统的实体造型平台—— ACIS ，包括 ACIS 的开发接口、数据结构、主要功能与特色以及在数控仿真系统开发中的应用；然后通过简要介绍数控加工的一些相关知识，引出了数控仿真系统加工环境的定义与该模块的实现方法；最后讲述了帮助文件的制作以及该系统帮助文件的结构。

First, the definition, significance, research emphases and status of NC machining verification technology are introduced in this paper. Then the platform―ACIS for the development of verification system, including its development interface, data structure, main functions, features and the application in the system is introduced. And, we indicate in brief the correlative knowledge of NC machining and then discuss the definition of the machining environment of NC machining verification system as well as the way that the module has been developed. Finally, we describe how to make Help Files and the structure of the Help Files in the system.

摘要本文首先对数控加工动态仿真技术的定义、意义、研究重点、研究状况进行了介绍；并介绍了可用于开发数控仿真系统的实体造型平台――ACIS，包括ACIS的开发接口、数据结构、主要功能与特色以及在数控仿真系统开发中的应用；然后通过简要介绍数控加工的一些相关知识，引出了数控仿真系统加工环境的定义与该模块的实现方法；最后讲述了帮助文件的制作以及该系统帮助文件的结构。

First of all, we should acknowledge that men and women have different roles to play in the society.

首先，我们应该承认，男女在社会中的角色是有差别的。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷