雅思寫作指導(dǎo)：下定義在議論文中的用途
“下定義”，可以給讀者一個(gè)直觀的概念或者清晰的思路，并且有利于后文的發(fā)展，而它本身并非只是字典上的解釋，可以靈活使用。接下來(lái)介紹一些它在大作文不同階段里的應(yīng)用：
(一) 引言段中的應(yīng)用
1. Globalization
Globalization—the international spread of products, ideas and information—is bringing the world closer together. But globalization is not a new concept. For thousands of years，nations have roamed the earth in search of new markets and new sources of raw materials for their own industries。
關(guān)于“全球化”這個(gè)名詞，考生并不陌生，但是如何用合理的語(yǔ)言來(lái)賦予它一個(gè)含義，這并非易事，上述的引言段就很好地做到了這一點(diǎn)，先是從字面上詮釋了“全球化”的定義，進(jìn)而又從實(shí)際生活角度賦予了它另外一層含義。
2. Telephone/Mobile phone
Imagine using smoking signals，carrier pigeons or riders on horseback to send an important message. Although those methods may sound strange，years ago people used them to communicate. Today，all a person has to do is pick up a telephone/mobile phone。
對(duì)于電話這一現(xiàn)代通訊工具，地球人都知道它是干嘛的，不過(guò)呢，我們可以從對(duì)于電話功能的定義上做文章，同樣也可以賦予它一個(gè)生動(dòng)的含義，并且一下子可以吸引讀者眼球。
3. Studying abroad
Every year，students around the world leave behind the comforts of home to pursue a study-abroad experience in a foreign country. While many would say that studying abroad is advantageous，some would argue otherwise。
出國(guó)留學(xué)同樣是一個(gè)非常熟悉的話題，若直接用字典上的定義直接去解釋它顯然多此一舉，因此，我們不妨從側(cè)面突破，通過(guò)引入大量學(xué)生出國(guó)留學(xué)的事實(shí)和目的來(lái)詮釋這個(gè)再也不能熟悉的話題，同樣可以起到很不錯(cuò)的效果。
4. Success
As Thomas Edison once said，“If you wish to succeed，you should use persistence as your good friend， experience as your reference，prudence as your brother and hope as your sentry. ”This essay is going to look at factors that constitute success。
“如果你希望成功，當(dāng)以恒心為良友、以經(jīng)驗(yàn)為參謀、以謹(jǐn)慎為兄弟、以希望為哨兵。”這是偉大的美國(guó)發(fā)明家愛(ài)迪生曾經(jīng)說(shuō)過(guò)的一句話，借助名人名言來(lái)下定義又是一種非常有效的開(kāi)頭方式，這樣做一方面揭示了文章接下來(lái)的主題，另一方面也增強(qiáng)了說(shuō)服力，可謂是一舉兩得。
(二) 主體段中的應(yīng)用
1. Some people think that universities should provide graduates with the knowledge and skills needed in the workplace. Others think that the true function of a university should be to give access to knowledge for its own sake，regardless of whether the course is useful to an employer. What，in your opinion，should be the main function of a university? (劍七Test 4)
以下是此題目一篇范文的第2個(gè)主體段：
However, reaching the conclusion that other functions，such as giving access to knowledge for its own sake，are no longer important is biased. For hundreds of years，especially in the west，the undergraduate education is，indeed， a liberal education，which means the undergraduates learn a wide range of curriculums such as psychology， economics， politics that has no direct relations to jobs. The upsides of this is that it firstly enables students to become broad-minded and help them lay a solid theoretical foundation，then they will be able to choose the most appropriate field based on their own interests for further studies。
這個(gè)段落的論述的中心是大學(xué)以傳授知識(shí)本身為目的，作者使用了“通才教育”這個(gè)在西方國(guó)家非常流行的教育方式為佐證，在給出“通才教育”定義的本身，又用定語(yǔ)從句補(bǔ)充到了和題目第2個(gè)論點(diǎn)間的關(guān)系，從而進(jìn)行了有力的對(duì)比，深化了段落中心。
2. Education
When people leave school，they wish they could breathe a sign of relief and leave learning behind. However，learning should last a lifetime. You exercise your body to stay strong，and you should exercise your mind to stay sharp. ……
在這個(gè)關(guān)于教育的話題中，作者在論述時(shí)用終身教育的好處來(lái)詮釋教育的長(zhǎng)期性和必要性，從而為下文的擴(kuò)展作了很好的鋪墊和過(guò)渡。
3. School should teach children academic subjects which will be beneficial to their future careers. Therefore，other subjects such as music and sports are not important. To what extent do you agree or disagree with this opinion?(08年5月22日A類考題)
Academic subjects，such as reading and writing，play a vital role in the education system. Apart from activating creativity and imagination，it helps students lay a solid foundation of knowledge. Some might say that academic subject is to a student as a rifle is to a soldier，without which he is unable to fulfill his mission……
在這個(gè)主體段中，作者在開(kāi)頭便舉出了一些學(xué)術(shù)課程的具體內(nèi)容，從而給讀者一個(gè)概念，同時(shí)也展現(xiàn)了作者對(duì)題目的解讀能力。接下來(lái)我們?cè)賮?lái)看一個(gè)相似的用法：
4. Why have not alternative energies already replaced fossil fuels?
There are also problems with production stability. The amount of energy we need varies throughout the day，and conventional energy production，such as coal and oil，can be increased or decreased based on these variations. Alternatives like wind and solar power are limited because they can only produce electricity when it is sunny or the wind is blowing。
在這篇分析型大作文里，作者通過(guò)對(duì)化石燃料和可替代燃料的對(duì)比，突出了前者的優(yōu)點(diǎn)，也揭示了后者的不足。通過(guò)將一個(gè)名詞范圍中的具體例子舉出，是下定義的另外一種詮釋。
綜上所述，下定義可用于議論文的開(kāi)頭或者主體段里，但是它一般不適用于用在結(jié)尾段中。除了字典上的定義外，建議考生還可以從這個(gè)名詞或短語(yǔ)的功能、目的、包含的具體例子等方面賦予它含義，這些方式都屬于下定義。
