"a normal, moderate level of unemployment is 5 percent, with one out of 20 workers unemployed"与“at any given time if a person knows approximately 50 workers, one or more will very likely be unemployed”的关系不是这样理解的吧。
Sharon的核心观点不是“失业率不高”而是“at any given time if a person knows approximately 50 workers, one or more will very likely be unemployed.”
我们将B取非: unemployment is normally concentrated in geographically isolated segments of the population。
则如果失业人群集中,换句话就是说非失业人也相对集中(因为如果非失业人平均分布,失业人就不会相对集中),就不是one or more will very likely be unemployed, 而是if a person knows approximately 50 workers, zero will very likely be unemployed