Come on—Everybody’s doing it. That whispered message, half invitation and half forcing, is what most of us think of when we hear the words peer pressure. It usually leads to no good—drinking, drugs and casual sex. But in her new book Join the Club, Tina Rosenberg contends that peer pressure can also be a positive force through what she calls the social cure, in which organizations and officials use the power of group dynamics to help individuals improve their lives and possibly the world.

    Rosenberg, the recipient of a Pulitzer Prize, offers a host of examples of the social cure in action: In South Carolina, a state-sponsored antismoking program called Rage Against the Haze sets out to make cigarettes uncool. In South Africa, an HIV-prevention initiative known as LoveLife recruits young people to promote safe sex among their peers.

    The idea seems promising, and Rosenberg is a perceptive observer. Her critique of the lameness of many public-health campaigns is spot-on: they fail to mobilize peer pressure for healthy habits, and they demonstrate a seriously flawed understanding of psychology. “Dare to be different, please don’t smoke!” pleads one billboard campaign aimed at reducing smoking among teenagers—teenagers, who desire nothing more than fitting in. Rosenberg argues convincingly that public-health advocates ought to take a page from advertisers, so skilled at applying peer pressure.

    But on the general effectiveness of the social cure, Rosenberg is less persuasive. Join the Club is filled with too much irrelevant detail and not enough exploration of the social and biological factors that make peer pressure so powerful. The most glaring flaw of the social cure as it’s presented here is that it doesn’t work very well for very long. Rage Against the Haze failed once state funding was cut. Evidence that the LoveLife program produces lasting changes is limited and mixed.

    There’s no doubt that our peer groups exert enormous influence on our behavior. An emerging body of research shows that positive health habits—as well as negative ones—spread through networks of friends via social communication. This is a subtle form of peer pressure: we unconsciously imitate the behavior we see every day.

    Far less certain, however, is how successfully experts and bureaucrats can select our peer groups and steer their activities in virtuous directions. It’s like the teacher who breaks up the troublemakers in the back row by pairing them with better-behaved classmates. The tactic never really works. And that’s the problem with a social cure engineered from the outside: in the real world, as in school, we insist on choosing our own friends.

答案精析：根据题干可定位至原文最后一段，该段首句指出，专家和官员选择同伴群体并将其行为导向正确方向的做法会有多成功（how successfully）还远不能确定（far less certain），后面又用老师将捣蛋的学生和表现良好的学生座位排在一起为例，说明这种方法并不奏效（never really works），可见同伴压力的作用值得怀疑，故D选项为正确答案。

错项排除：原文虽然提到同伴压力会导致不良后果，但那是大家通常的看法，并非作者的观点，也不是最后一段的内容，故A选项错误。B、C选项与原文表达的含义相悖，故错误。

长难句分析：Far less certain, however, is how successfully experts and bureaucrats can select our peer groups and steer their activities in virtuous directions.

本句为复合句，句子主干为Far less certain…is how…，句子使用了倒装结构，how引导的主语从句为句子的主语，正常语序为how…is far less certain。主语从句使用了and连接的并列谓语select和steer。

句意为：然而，专家和官员能在多大程度上成功选择同伴群体并将其行为导向正确的方向还远不能确定。