What is coherence?
Coherence generally means natural or reasonable connection. In language communication, it refers to a logical, orderly and aesthetical relationship between parts, in speech, writing, or argument. In other words, When sentences, ideas, and details fit together clearly, readers can follow along easily, the ideas tie together smoothly and clearly, and the writing is coherent. Coherence is an important principle which we should abide by in academic writing.
Coherence in a paragraph refers to the way the sentences are arranged and to their relationship to one another. When a paragraph is coherent, the sentences are arranged in a clear and logical order, the transitions are smooth and natural, and ideas flow smoothly and gracefully from one sentence to the next. As a result, the reader finds it easy to follow the writer's train of thought.
Practical methods for achieving coherence
1.Repetition of a Key Term or Phrase （page 150）
Example: The problem with contemporary art is that it is not easily understood by most people. Contemporary art is deliberately abstract, and that means it leaves the viewer wondering what she is looking at.
Surfing-the art of riding a wave on a pointed board-is the wildest, fastest natural water sport known to man. In recent years, surfing has developed into a major sport around the world.
2. Pronouns（page 150）
Example: When scientific experiments do not work out as expected, they are often considered failures until some other scientist tries them again. Those that work out better the second time around are the ones that promise the most rewards.
No organ of the body is less appreciated than the skin. One of our biggest and busiest organs- and the most telltale-it mirrors of our health, our age, and our race.
4.Sentence Patterns （page 152）
Example: (from a speech by President John F. Kennedy) And so, my fellow Americans: ask not what your country can do for you--ask what you can do for