2. C 推理判断题。由第二段第二、三、四句可知，像Debbie Downer这样的人是不体谅别人的人，故选C。 3. B 细节理解题。由第三段最后一句“He found that science amazed Times’ readers and made them want to share this positive feeling with others”可知，选B。 4. D 选择标题题。由首段But后的内容，特别是最后一句“scientists have found that good news can spread faster and farther than disasters and sob stories”，以及最后一段，特别是“The more positive an article, the more likely it was to be shared”可知，在社交网上正面消息比负面消息更易传播。故选D。