行文的逻辑性常常要靠适当的转换词语及其他手段来实现。请读下面这一段文字并找出文中用以承上启下的词语：

Walter’s goal in life was to become a successful surgeon. First, though, he had to get through high school, so he concentrated all his efforts on his studies --- in particular, biology, chemistry, and math. Because he worked constantly on these subjects, Walter became proficient in them; however, Walter forgot that he needed to master other subjects besides those he had chosen. As a result, during his junior year of high school, Walter failed both English and Latin. Consequently, he had to repeat these subjects and he was almost unable to graduate on schedule. Finally, on June 6, Walter achieved the first step toward realizing his goal.

本文中起承上启下的词语有两种，一种是转换词语（transitional words or phrases），另一种是起转换作用的其他连接手段（linking devices）。前者依次有：first, though, so, in particular, and, because, however, besides, as a result, both…and, consequently, and, finally.后者依次是：he, he, his, his, he, these, them, he, those, his, he, these, his. 本段中共有词汇105个，所使用的转换词语及其他连接用语共26个词，约占该段总词汇量的四分之一。由此可见，掌握好transitions不仅对行文的流（smoothness）有益，而且对于学生在半个小时内写足四级短文所要求的120个词也是不无好处的。

一个段落里如果没有transitions也就很难有coherence了.我们看下面一个例子：Speaking and writing are different in many ways. Speech depends on sounds. Writing uses written symbols. Speech developed about 500 000 years ago. Written language is a recent development. It was invented only about six thousand years ago. Speech is usually informal. The word choice of writing is often relatively formal. Pronunciation and accent often tell where the speaker is from. Pronunciation and accent are ignored in writing. A standard diction and spelling system prevails in the written language of most countries. Speech relies on gesture, loudness, and rise and fall of the voice. Writing lacks gesture, loudness and the rise and fall of the voice. Careful speakers and writers are aware of the differences.

本段中除了第6句开头出现一个起过渡作用的＂it＂之外，没有使用其他的过渡词语.这样，文中出现许多重复的词语，全段读起来也显得生硬而不自然。如果加上必要的过渡词语来修饰的话，这一段就成了下面一个流畅连贯的段落：

Speaking and writing are different in many ways. Speech depends on sounds; writing, on the other hand, uses written symbols. Speech was developed about 500 000 years ago, but written language is a recent development, invented only about six thousand years ago. Speech is usually informal, while the word choice of writing, by contrast, is often relatively formal. Although pronunciation and accent often tell where the speaker is from, they are ignored in wiring because a standard diction and spelling system prevails in most countries. Speech relies on gesture, loudness, and the rise and fall of the voice, but writing lacks these features. Careful speakers and writers are aware of the differences．

4、有损连贯性的几种情况：

考生在写作中经常出现下面几种错误：

1、不必要的改变时态，比如：

In the movie, Robert Redford was a spy. He goes to his office where he found everybody dead. Other spies wanted to kill him, so he takes refuge with Julie Christie. At her house, he had waited for the heat to die down, but they come after him anyway.

2、不必要的改变单复数，比如：

Everybody looks for satisfaction in his life. They want to be happy. But if he seeks only pleasure in the short run, the person will soon run out of pleasure and life will catch up to him. They need to pursue the deeper pleasure of satisfaction in work and in relationships.

3、不必要的改变人称，比如：

Now more than ever, parents need to be in touch with their children’s activities because modern life has the tendency to cause cleavages in the family. You need to arrange family like it so that family members will do things together and know one another. You need to give up isolated pleasures of your own and realize that parents have a set of obligations to sponsor togetherness and therefore sponsor knowledge.

因此写作中，一定要注意时态，人称以及数的变化是否正确，要注意保持一致。