Several years into a campaign to get kids to eat better and exercise more, child obesity rates have appeared to stabilize, and might be poised for a reversal. But a study published Monday in the journal PNAS suggests that among adolescents, the【C1】______signs are limited to those from better-educated, more【C2】______families. Among teens from poorer, less well-educated families, obesity has【C3】______to rise. That class-gap was not【C4】______in younger children. But as children neared【C5】______, the class differences became increasingly obvious. 【C6】______between rich and poor in obesity rates are not new, and they are only one of many health gaps that make poor patients sicker and more likely to die【C7】______than richer ones. But if the public health message on obesity "has not diffused【C8】______across the population," this gap could 【C9】______efforts to stem a tidal wave of【C10】______obesity-related diseases in the years ahead. Researchers from Harvard University's Kennedy School of Government found that【C11】______activity may account largely for the【C12】______trend in obesity between rich and poor. If public health experts are to prevent childhood obesity and【C13】______drive down future obesity among adults, they'll have to figure out【C14】______less advantaged kids don't get as much exercise, the authors of the latest study say. Yes, lack of 【C15】______centers, playgrounds, and streets and sidewalks that【C16】______walking, biking and playing are important, they wrote. But, they added, "this is not the whole story." Among children with parents who【C17】______high on the socioeconomic scale, participation in high school sports and clubs has increased. But among their【C18】______from families of lower educational 【C19】______and income, such participation has【C20】______.
【答案解析】解析：根据下文提及的playgrounds，streets，sidewalks，walking，biking and playing等信息，可推断解释发展出这种差异的原因应该是跟“身体活动”有关，故选D项physical“身体的”。
单选题
【C12】
【正确答案】
A
【答案解析】解析：第2段已提及贫富之间肥胖率的变化趋势是不一致的(the signs are limited to those from better-educated…)，再结合原文提及的class-gap和class differences，可推断此处的trend应该是不同的，故选A项divergent“相异的”。
单选题
【C13】
【正确答案】
C
【答案解析】解析：句中prevent“预防”和drive down“降低”、childhood“儿童期”和adults“成年期”之间的先后顺序提示drive down future obesity among adults是prevent childhood obesity的目的，故选表目的的C项thereby“从而”。
【答案解析】解析：从句中的——walking，biking是对…centers，playgrounds，and streets and sidewalks的说明。上文提出关于弱势孩子“得不到足够锻炼”的问题，其回答为“yes，lack of．．．sidewalks…”，也就是说这些场所是能帮助人们得到锻炼的。故选A项encourage“鼓励”。