If a reader is lost, it is generally because the writer has not been careful enough to keep him on the path. This carelessness can take any number of forms. Perhaps a sentence is so excessively cluttered that the reader, hacking his way through the verbiage, simply doesn’t know what it means. Perhaps a sentence has been so shoddily constructed that the reader could read it in any of several ways. Perhaps the writer has switched tenses, or has switched pronouns in mid-sentence, so the reader loses track of when the action took place or who is talking. Perhaps sentence B is not logical sequel to sentence A ---- the writer, in whose head the connection is clear, has not bothered to provide the missing link. Perhaps the writer has used an important word incorrectly by not taking the trouble to look it up. He may think that "sanguine" and "sanguinary" mean the same thing, but the difference is a bloody big one. The reader can only infer what the writer is trying to imply.
I do not understand why people confuse my Siamese cat, Prissy, with the one I had several years ago, Henry. The two cats are only alike in breed. Prissy, a quiet, feminine feline, loves me dearly but not possessively. She likes to keep her distance from people, exert her independence and is never so rude as to beg, lick, or sniff unceremoniously. Her usual posture is sitting upright, eyes closed, perfectly still. Prissy is a very proper cat. Henry, on the other hand, loved me dearly but possessively. He was my shadow from morning till night. He expected me to constantly entertain him. Henry never cared who saw him do anything, whether it was decorous or not, and he usually offended my friends in some way. The cat made himself quite comfortable, on the top of the television, across stranger’s feet or laps, in beds, drawers, sacks, closets, or nooks. The difference between them is imperceptible to strangers.
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不仅对行文的流畅(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.
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.
