大学英语：The difference between popular and

　　7. The difference between popular and learned words may be easily seen in a few examples.

　　8. Must have done sth. 表示对过去的事情进行推测。E.g. We must have passed several years of our lives before learning the word vivacious.在我们学到vivacious这个单词时，我们有可能已经度过了生命中的好几年了。

　　9. Popular（adj.流行的）-popularity（n.流行）；sound-（adj.）有道理的

　　10. Opinions come up  产生观点

　　11. Its presence in the English vocabulary is due to books and the cultivation of literature rather than to the actual needs of ordinary conversation.书卷词汇在英语词汇中的存在是因为书籍和文学修养的需要，而不是因为普通对话的需要。