Panda bear is a kind of docile lovely animal in the southwest of China. Its cherubic appearance and awkward movement appeals to not only children but also adults. It symbolizes the spirit of peace and harmony, which is cherished by Chinese people. Expansion of human activities to wild areas has caused a sharp decrease in the number of panda bears.
这段话由四句组成，彼此之间存在着明显的联系，论证的都是中国大熊猫的情况。排除语法，文字优美等诸多考虑，这段话给人的感觉是四个孤立的句子，而不是一段文章。其原因之一，也被笔者认为是最重要的一个原因，是它缺乏必要的过渡（Transitions），文中主题之间缺乏有机联系导致文章缺乏必要的连贯性。这一问题也是学生在写作实践中普遍存在的现象。本文的目的就是介绍英文写作中transitions的使用。
作为考试项目教师，出于通过考试的目的，注意在文章中必要的连接也显得尤其重要。在诸多北美考试的写作评分标准中，都出现过与之相关的要求，比如
*"displays unity, progression, and coherence, though connection of ideas may be occasionally obscured" (iBT Independent Writing 3分评分标准)
*"develops and organizes ideas satisfactorily but may notconnect them with transitions"
（GRE Argument 4分评分标准）
*"is limited in its organization or focus, or may demonstrate some lapses in coherence or progression of ideas" (Sat Write an Essay 3分评分标准)
各种考试中不约而同的出现对于coherence，connection，transitions等概念的要求，而且这部分做的不到位都会影响考试写作部分的成绩，其重要性可见一斑。上面三个词的翻译为"连贯性"，"连接"和"过渡"，而connection和transitions在这里可以被理解为同义词，笔者认为就是达到coherence这一目的的重要手段之一(还有一些其他方法，比如重述和首尾的呼应)。
那么到底甚么是Transitions呢？在GRE考试中又被称作Transitional devices，连接元件。笔者尝试对之做出定义：Transitions是出现在文章中的一种词，短语甚至句子，其目的是用来表明它前后两部分之间的逻辑关系的，它的用处是能够帮助读者自然地从作者的一个idea转移到下一个idea，使用的结果可以使文章的逻辑性更强，更加连贯。打个比方来说，它很像道路上引导旅者的标志牌（They are like the road signs that guide travelers-College Writing Skills）。之所以说"前后两部分"，是因为Transitions的前后可能是两个段落，两句话，甚至两个单词，它们彼此之间都会存在各种各样的逻辑关系，比如说：
*Addition: and, in addition, additionally, one, another, first of all, secondly, furthermore, moreover
*Time: then, after, before, since, once, until, meanwhile, now, during
*Space: next to, across, above, below, nearby
*Change-of-direction: but, yet, however, otherwise, nevertheless, although, in contrast, on the contrary
*Conclusion: because, so, therefore, as a result, consequently, thus, in summary, conclude
其实还有很多其他关系，其他的词，这几种是比较常见的。我们发现这种transitions的出现方式非常多样，包含了很多词性：连词，介词，副词，动词等等，还有很多短语，所以把它称之为Transitional devices是非常恰当的。
针对Transitional devices前后可以是段落，句子以及单词，我们分别举几个例子：
*Among paragraphs：
In the first place, human always like exploring the world around, especially mysterious fields…………
Besides human's curiosity, to explore dangerous fields draws them away from daily routine and boredom.……
Finally, although these dangerous activities may not bring us any material reward, they bring forth a lot of psychological benefits.……
这是一篇托福作文的三个中间段的topic sentence，可以看出三段分别论证了人类参加危险运动的三条理由（好奇心，找刺激以及精神的愉悦），彼此之间的并列关系，是通过In the first place, Besides，Finally这三个Transitional devices来体现的
另外，段落之间也有可能出现转折逻辑关系，相应的连接语也会发生变化，比如：
One reason for my fundamental agreement with the speaker is that withholding some personal information is necessary to gain and maintain political leadership.……
Another reason why I essentially agree with the speaker is that fully disclosing to the public certain types of information would threaten public safety and perhaps even national security.……
Having recognized that withholding information from the public is often necessary to serve the interests of that public, legitimate political leadership nevertheless requires forthrightness with the citizenry as to the leader's motives and agenda.……
上面是一篇GRE北美范文的三个中间段的topic sentences，可以发现，前两段之间是并列关系（one reason/another reason）,而第三段和前两段之间就是转折关系（nevertheless）
*Among sentences:
Office workers' time is hardly enough for their own work. As a result, big companies lack necessary team spirit, rendering employees' emotional distance from each other.
这两句话论证了为什么大公司缺乏必要的团队精神，员工之间感情淡漠，各自忙于工作是原因，缺乏team spirit是结果，所以前后两句话之间通过连接语As a result表明了因果逻辑关系。同样的，句子之间也有并列与转折关系：
For example, foods in western world, such as cheese, jam and butter, are now becoming familiar and popular in China. By the same token, more and more products with Chinese style can be found in American markets.（并列）
In the past, people may only obtain information from some traditional media, such as televisions, books, or newspapers. However, today people are able to receive the same material through computers.（转折）
*Among words：
Instead ofobtaining splendid grade in exams, students' main assignment is to perceive the way to search knowledge they want.
这句话中的instead of 前后实际上是两个具有名词特性的短语，分词短语obtaining splendid grade in exams，和介词短语to perceive the way to search knowledge they want。这两部分之间具有转折关系，用Instead of来体现. 而用来表达单词中的并列和因果关系的连接语就是我们很常见的and还有because of，这个很简单就不举例子。
在写作文章中充分合理地加入这种Transitional devices，就可以在很大程度上增加文章的连贯性，比如还是本文开头的那段话，稍加修改之后变成了：
Panda bear is a kind of docile lovely animal in the southwest of China. Because of its cherubic appearance and awkward movement, it also symbolizes the spirit of peace and harmony, which is cherished by Chinese people. However, expansion of human activities to wild areas has caused a sharp decrease in the number of panda bears.
通过判断，我们发现修改前的一二两句之间存在因果关系，因此加入because of 将它们连在了一起；而修改前的第三句和前两句之间是一个并列关系，因此加入了also；最后一句话的意思和前面明显出现了转折，通过however来体现这种转折关系。经过修改之后，几句话被有机地结合在了一起，形成了一段篇章而非四个独立的句子。
不过，在充分使用各种连接语的同时，也应该注意不同词性连接语的用法，比如连词很自由，and，but，so这些连词的后面可以跟名词或者句子。但是介词（介词短语）后面只能跟名词，比如because of， instead of，in addition to等等；而副词（副词性短语）的后面只能加句子，比如however, in addition, as a result等等。
刚才看到的是一些词或短语充当transitions的情况，其实transitions还有另外一种体现方式就是transitional sentences，比如很常见的让步状语从句：
Even if traveling with a companion could bring us financial and some other benefits, this type conducts our traveling experience to a mechanical boring event.
从这个句子中可以看出由even if引导的让步状语从句，说明了这句话之前的内容论证的是traveling with a companion的好处，而主句则是讲这种方式让我们的旅行成为意见机械无聊的行为，也是后面要论证的一个主题，前后两部分之间显然是转折的逻辑关系。出现在文章之中可以有效地连接上下文，使之变得连贯：
I concede that traveling with a companion may have one or more benefits. One ofthe most obvious advantages is saving money. In other words, Traveling in a group would be much cheaper than traveling alone. In my observation, travel agency, the most common group-travel organization in China, reserves a prerogative of paying considerably less on tickets fees, traffic costs, and so forth than individuals. Moreover, individuals have to purchase some necessaries, like tent, when traveling by themselves, but if we go hiking with one or two friends, we could pay for these shared outfits together. Another advantage of traveling in a group is that we have accompaniers to communicate with. But I believe that this advantage is only desirable for those who often feel lonely and like clatter.
Even if traveling with a companion could bring us financial and some other benefits, this type conducts our traveling experience to a mechanical boring event.People might not arrange his or her own plan if he or she is traveling in a group, because all group members should be restricted by lots of rules, such as the place where we have to reside, the time when we can play or must gather, etc. For instance, when I followed a travel agency to Hangzhou which is one of the most beautiful cities of China last year, hardly did I finish my visit because of the time restriction ordered by the cicerone. In contrast, if I would have traveled alone, I could manage my journey flexibly. To some extent, losing freedom means losing interest in a team traveling.
另外一些其他的句子也有这种作用，例如：After recognizing the advantages of using land for farming, housing and so forth, however, we should also save some land inhabited by endangered species.中文写作中的承上启下的句子就是这个意思，而承上启下这个成语非常精确地表明了transitional sentences的作用。
总之，一篇文章是一个完整的有机体，好像一部机器，每个段落，每个句子，每个单词都是机器的一个部件，而Transitions就像是连接这些部件的螺丝，如果缺乏，这个机器就会散落，文章也不能构成篇章，顶多就是一堆句子群而已。连接语虽然不难，但是要将它们合理充分多样地加入文章之中，仍然需要大量练习。
References：
John Langan, College Writing Skills, 2007, Foreign Language Teaching and Research Press
Halliday, M.A.K, and Hasan, R. Cohesion in English, 1976, London, Longman
Mark Alan Stewart, J. D, 《GRE北美范文》, 2004, 世界知识出版社