b. a、b优势均难的割舍，只好依情况而定在结论部分说清楚在什么条件选a, 在什么条件选b．

　　下面重点介绍第①、②种类型议论文的写作模式.

　　2. “一分为二”观点的议论文模式

　　introduction

　　第1段:nowadays more and more people．．．/．．．plays an important part in．．．. like everything else,．．．has/have both favorable and unfavorable aspects/both advantages and disadvantages. generally, the favorable aspects/advantages can be listed as follows.

　　main body

　　第2段：firstly,.. secondly,…in addition/what’s more…

　　第3段: every coin has two sides. the negative aspects/disadvantages are also apparent/obvious. to begin with…; to make matters worse…; worse of all…

　　conclusion

　　第4段: through above analysis/all things considered, we can see that the positive aspects/advantages outweigh the negative ones/disadvantages. therefore…

　　例文1. 看电视的利与弊 advantages and disadvantages of watching tv

　　nowadays more and more people like to watch tv. so tv plays a very important part in our life. but watching tv has both advantages and disadvantages. generally, the advantages can be listed as follows.

　　firstly, you can expand your knowledge by watching tv. as we all know, learning things by tv is much faster than by listening to the radio or just by reading books. for it has colorful pictures as well as wonderful music.

　　secondly, you may know anybody you want to know such as famous singers, super stars, scientists and so on.

　　what’s more, you can go everywhere by traveling programs. let’s suppose, if you like traveling very much, but you have to work on weekends or holidays, you must be very sad. and now open your tv and it’ll take you to anywhere.

　　every coin has two sides. the disadvantages are also obvious. for example, watching too much tv can easily become short-sighted, especially for children and students. to make matters worse, some young students are keen on watching tv so that they give up their studies gradually.

　　through above analysis, i think watching tv is a way of studying, it is good for us to watch tv. but when we watch tv, we should make a plan otherwise watching tv will destroy our life.

　　例文2. 谈谈出国留学的利与弊 where to attend a college

　　nowadays more and more young people are going to study abroad. like everything else, studying abroad has both favorable and unfavorable aspects. generally, the favorable aspects can be listed as follows.

　　firstly, they think by attending a college in a foreign country they can learn not only useful knowledge, but also the culture and customs of other nations. secondly, they can take advantage of this opportunity to gain a good command of the foreign language they are learning very quickly. moreover, they can meet different people and experience different cultures, which may help to broaden their views.

　　every coin has two sides. the negative aspects are also apparent. the costs are much higher than those in their native country. most overseas students have to work for a living, which can’t allow them to pay all their attention to study. what’s more, they may feel very lonely.

　　through above analysis, we can see that the positive aspects outweigh the negative ones. therefore, i am in favor of going abroad to study.