比较型——通过对过去、现在两种不同的倾向、观点的比较，引出文章要讨论的观点。

　　1.For years, ...had been viewed as .... But people are taking a fresh look now. With the growing ..., people ....

　　多年来，……一直被视为……。但是人们现在正在焕然一新。 随着...的增长，人们....

　　2.People used to think that ... (In the past, ....) But people now share this new idea.

　　人们曾经以为……(过去是……)，但是现在人们分享了这个新想法。