Ever since humans have lived on the earth, they have made use of various forms of communication. Generally, this expression of thoughts and feelings has been in the form of oral speech. When there is a language barrier, communication is accomplished through sign language in which motions stand for letters, words and ideas. Tourists and the people unable to hear or speak have had to resort to this form of expression. Many of these symbols of whole words are very vivid and exact and can be used internationally; spelling, however, cannot. Body language transmits ideas or thoughts by certain actions, either intentionally or unintentionally. A nod signifies approval, while shaking the head indicates a negative reaction. Other forms of nonlinguistic language can be found in signal flags, Morse code, and picture signs.
在该段中为了说明topic sentence中的 "various forms of communication"，作者将其分为oral speech, sign language, body language及other forms of nonlinguistic language，并逐加阐述。
采用这种方法的段落并没有标志突出的连接词，所述各项均为平行并列关系，所以没有明显的主次之分。
6． 因果分析法(cause and effect)
在阐述某一现象的段落中，常采用因果分析法。例如：
The role of women in today`s society is changing. One reason is that women have begun to assert themselves as independent people through the women`s movement. Also, women are aware of the alternatives to staying at home. Another reason is that increasing numbers of women who enter new fields and interests serve as role models for other women. Moreover, men are becoming more conscious of the abilities of women and have begun to view their independence positively.
本段中，主题句提出了一种社会现象，推展句则对产生这种现象的原因作出各种解释。 常用于因果分析法的连接词有：because, so, as a result等。
7． 定义法(definition)
在科普文章的写作中，定义法是必不可少的。通过下定义，可以使读者对该事物有一个更直接的认识。