coherence is product of many different factors ,which combine to make every paragraph sentence ,and every phrase contribute to the meaning whole piece... To achieve paragraph unity,a writer must ensure two thongs only:first,the paragraph must have a single generalization that serves as the focus of attention that is a topic sentence.Secondly ,a writer must control the content of every other sentence in the body's paragraph such as that it contains more specific information that the topic sentence and (b) it maintains the same focus of attention as the topic sentence...
