[9급 지방직 영어 2008년 9번]

Given the general knowledge of the health risks of smoking, it is no wonder that the majority of smokers have tried at some time in their lives to quit. ① But in most cases their attempts have been unsuccessful. People begin smoking, often when they are adolescents, for a variety of reasons, including the example of parents and pressure from peers. ② The installation of smoke detectors in buildings is required by law. ③ If others in one's group of friends are starting to smoke, it can be hard to resist going along with the crowd. ④ Once people start smoking, they are likely to indulge in it.