Double negation is also called “double negative”or “negation of negation” (Wu & Yang, 2011) . Double negation negates twice, and make its negative meaning cancel each other out and have a sure sense. The tone of double negation is stronger than the positive sentence and double negation always aims to emphasis.
2.2 Previous Study on Negation and Negative Words
    Chinese scholars have conducted many tests and researches to study the use of negative words in English-Chinese translation. Generally speaking,these studies can be pided into two different kinds in terms of their starting perspectives. 否定句英汉互译中的否定词使用研究(3):http://www.youerw.com/yingyu/lunwen_20122.html