Introduction
引言部分介绍此项研究的主题、背景、范畴，并说明全文的结构，便于读者阅读，一般包含几项内容：
1. 背景介绍
2. 现有问题
3. 研究目标
4. 篇章结构
1.背景介绍
…has been a hot topic in … research.
在„研究中，„已成为研究热点。
…is the … problem that has received the most attention in the … literature.
在„文献中，„是受到最多关注的„问题。
…have attracted much attention from academia.
„已经引起学术界的很大关注。
…has been of considerable interest to the … community in recent years.
近年来，„已经引起„界的极大关注。
It is well known that …
众所周知，„
It is reported that …
据报导，„
There have been studies highlighting …
此前已经有一些针对„的研究。
Over the past 3 decades, …
在过去的三十年，„
The previous work on … has indicated that …
先前关于„的研表明„
Recent experiments by … have suggested …
最近„做的实验表明„
Recent experiments in this area suggested that …
这个领域的最新实验表明„
The approach adopted extensively is called …
被广泛采用的方法称为„
Several researchers have theoretically investigated …
有几个研究者已经从理论上考察了„
In most studies of …, … has been emphasized with attention being given to …
在大多数对„的研究中，„受到高度重视，人们关注的是„
Industrial application of … is becoming increasingly common.
„的工业化应用日益普及。
The approaches fall into two major groups.
现有方法主要分成两类。
The approaches can be divided into two general classes.
现有方法一般分成两类。
The approaches may be classified into two categories.
现有方法可以分成两类。
The approaches are of two broad.
现有方法分成两类。
2.该领域现有问题
Great progress has been made in this field, but/however, nevertheless …
虽然这个领域已经取得重大进步，但是„
A part of the explanation could lie in … However, …
部分解释可能在于„。但是，„
The study of … gives rise to two main difficulties: one is …; the other is …
研究遇到两个主要困难：一个是„;另一个是„
Also, the consideration of … alone cannot explain the observed fact that …
单独考虑„无法解释观察到的事实，即„
From the above discussion, it appears that at present neither … nor …
从以上讨论可知，目前既不„也不„
Despite the recent progress reviewed in …, there is no generally accepted theory concerning…
除了已经在„中回顾的最新进展，还没有关于„的广为接受的理论。
The only research that I am aware of that has dealt directly with the problem of … is a series of papers by …
我所知道的直接针对„问题的唯一研究是„发表的一系列论文。
Experiments of this kind have not been performed.
这种实验还没有人做过。
Until now no field experiments of … have been reported.
目前为此，还没有关于„现场实验的报导。
The method we used differs greatly from the one reported last year.
我们使用的方法与去年报导的有很大不同。
No clear advancement has so far been seen in …
在„领域，还没有出现明显的进展。
The data available in literature failed to prove that …
文献中的数据无法证明„
3.引出自己的研究目标
We propose … as a solution to address this problem.
We build several different models to address these issues and to improve … for the benefit of …
我们构建了几个不同的模型，以应对这些问题，并针对„改进„
In this paper, … is investigated/studied/discussed/presented 本文研究„
