如何写说明原因段和说明方法段


　　一、说明原因段
　　说明原因段一般出现在图表阐释类和说明现象类作文的第二段，其基本句型构造是：先用一句话引出下文对现象或问题原因的说明，这是段落的主题句；然后用3-5句话列举2-3点具体的原因，以支持主题句。

　　例
　　Directions : For this part , you are allowed 30 minutes to write a essay entitled What Electives to Choose . You should write at least 120 words following the outline given below in Chinese :
　　1.各大学开设了各种各样的选修课。
　　2.学生因为各种原因选择了不同的选修课。
　　3.以你自己为例……

　　第二段：说明原因段
　　(1) There are many different factors deciding what electives the students choose . (2) Among all these factors , the interest of the students plays a very important role . (3) The students , of courses , would like to learn what he or she is interested in . (4) Moreover , many students will consider whether they could learn some practical skill by the elective , because nowadays companies are placing emphasis on a candidate's practical skills . (5) Besides , the ability and the prestige of the teacher is also an important factor influencing the student's choice .