这是篇段首句续写式作文。经分析，文中所给的前两段的段首句均可作为该段的主题句。第三段中，可根据所给的段首句暗示的写作方向，得出结论，并以此为该段主题句。故第三段主题句为：One must consider both sides of the factors carefully before making up his mind。由此完成通篇构思，其全文和各段框架具体构思如下：
1.Attending school abroad has many advantages.
2.There are also some disadvantages.
3.One must consider both sides Of factors carefully.
第一段 Topic Sentence Attending school abroad has many advantages.
l. widen our vision
2. travel widely
3. improve the second foreign language
4. acquire updated knowledge
第二段 Topic Sentence There are also many disadvantages。
1. language barrier
3. high tuition and cost of living
第三段 Topic Sentence One must consider both sides of the factors carefully.
1. good to study the subject weak in our country
2. should consider the disadvantages
widen our visionhorizon 开阔视野
get acquainted with 了解
first-rate facilities 一流设备
language barrier 语言障碍
... In the first place, … Secondly, … Thirdly, …
But the most important thing... For all these...
However, … As a result, ... Besides, ... Furthermore, …
Therefore, ... On the whole, … But on the other hand, ...
1. Attending school abroad has many advantages.
2. Attending school abroad has many positive aspects.
3. Studying abroad has many strong points.
4. Studying abroad has many favorable aspects.
1. But on the other hand, one must not lose sight of the disadvantages.
2. But most important of all, one should not neglect the disadvantages of studying abroad.
3. Finally, one should always think carefully before making up one's mind.
4. Finally, everything depends on his personal financial status. If the advantages can outweigh the disadvantages, he should make up his mind to study abroad. Otherwise, it's advisable to study at home.
Attending school abroad has many advantages. In the first place, by looking at our own country from the outside, we can best see the strong points of our nation, and therefore widen our vision and broaden our minds. Secondly, while studying in a foreign country, we can travel widely, visiting famous scenic spots and making friends with the local people. Thirdly, we can use the foreign language in our daily life so that our ability in the second language may be improved quickly. But the most important thing in attending a foreign university is to get acquainted with the latest knowledge in science and technology and make use of the first-rate facilities available. For all these advantages, it is really worthwhile to go abroad for further studies.
However, as everything has two sides, there are also some disadvantages in attending a foreign university. The most serious problem is the language barrier. Most of the students who are ready to go abroad do not have adequate proficiency in the language spoken there. As a result, on arriving there, they will find it difficult to understand what the instructors are saying. Besides, for lack of knowledge of the customs and way of life of the local people, they may constantly run into trouble in dealing with various situations. Therefore, misunderstandings often arise. Furthermore, the cost of living is much higher than that in our country, so most students have to find part-time jobs in order to help support themselves. Faced with these difficulties, many students find themselves unable to pay full attention to their studies and some students may even fail in their courses and learn little, even some have to return to their motherland.
Therefore, given an opportunity to attend a school abroad, one must consider both sides of the factors carefully before making up his mind. On the whole, it is a good thing to go and study abroad particularly when the subject is very weak or not available in our country. But on the other hand, one must not lose sight of the disadvantages.