posts, scientists have found that good news can spread faster and farther than disasters and sob stories.

Researchers analyzing word-of-mouth communicate-e-mails, Web posts and reviews, face-to-face conversations-found that it tended to be more positive than negative, but that didn't necessarily mean people preferred positive news. Was positive news shared more often simply because people experienced more good things than bad things? To test for that possibility, Dr. Berger looked at how people spread a particular set of news stories: thousands of articles on The New York Times' website. He and a Penn colleague analyzed the "most e-mailed" list for six months. One of his first findings was that articles in the science section were much more likely to make the list than non-science articles. He found that science amazed Times' readers and made them want to share this positive feeling with other.

Readers also tended to share articles that were exciting or funny, or that inspired negative feelings like anger or anxiety, but not articles that left them merely sad. They needed to be aroused one way or the other, and they preferred good news to bad. The more positive an article, the more likely it was to be shared, as Dr. Berger explains in his new book, " Contagious: Why Things Catch On."

24.What do the classic rules mentioned in the text apply to?

A. News reports B. Research papers.

C. Private e-mails. D. Daily conversations.

25.What can we infer about people like Debbie Downer?

A. They're socially inactive. B. They're good at telling stories.

C. They're inconsiderate of others. D. They're careful with their words.

26.Which tended to be the most e-mailed according to Dr. Berger's research?

A. Sports news. B. Science articles.