第20题: [单项选择]The main idea of the passage is______. A. to explain what advertisements are B. to reveal the purposes of advertisers C. to tell the reader how to read advertisements D. to classify advertisements into several types 参考答案:C 答案解析:[详细解答]此题为主旨题。文章第一段谈到报纸杂志上的广告供读者阅读和观赏,以期引起人们的购买欲望。第二段谈到广告商们想要人们相信他们的产品的重要性。有些广告甚至适时地表明对一些话题的看法,以期影响读者