A、Pneumonia. B、Heart disease. C、AIDS. D、Drug abuse. B事实细节题。本题问的是工业化国家人们生命的第一大杀手是什么。短文结尾部分明确提到，心脏病已经成为威胁大多数工业化国家人们生命的第一大杀手。

It is said that happiness is contagious(会传播的). The supporting evidence is everywhere: from the streets of Rio during Carnival to more obscure celebrations elsewhere in the world. And long-term happiness may also be healthy. New York researcher Dr. Karina Davidson certainly thinks so.(16)Dr. Davidson is a lead researcher in a ten-year study of more than 1 700 healthy men and women.(17)The study revealed that people who are happy and content with their lives are 22% less likely than unhappy people to have a heart attack or suffer from symptoms of heart disease. We know that there is a direct physiological impact on the body of experiencing happiness or satisfaction or enjoyment. So, when you sit down and watch a movie, or read a book that you really enjoy, your stress hormones go down and some cultural barrier reflex system is actually up regulated. We know an animal study said those things across time actually protect the heart. The observational study is the first to show an independent relationship between positive emotions and coronary(冠状动脉的)heart disease. But Dr. Davidson stresses that more work and clinical trials are needed before any treatment recommendations can be made. She says, though, that the study is the first step in providing doctors better insight and how to interact with their patients.(18)Heart disease is the leading killer of men and women in most industrialized countries. Dr. Davidson says she hopes her report will shine a light on a new approach for prevention.
16. Who is Dr. Davidson?
17. What kind of people are easy to be attacked by heart disease?
18. What is the leading killer of people in industrialized countries?