7. An emerging body of research shows that positive health habits—as well as negative ones — spread through networks of friends via social communication.

【分析】复合句。句子主干为 body...shows that...。that 引导的从句作 shows 的宾语，该从句中两个破折号之间的成分作插入语对从从句主语进行补充说明。

【译文】一个新兴的研究机构指出，积极健康的生活习惯和消极的习惯都可以通过社交活动在朋友圈中传播。

【点拨】emerging 在句中的意思是“新兴的”。

8. Far less certain, however, is how successfully experts and bureaucrats can select our peer groups and steer their activities in virtuous directions.

【分析】复合句。句子为倒装结构，表语 Far less certain 提前。 however 为插入语。how 引导主语从句，该主语从句的主干为 experts and bureaucrats can select...groups and steer their activities...。

【译文】然而，至于专家和官员如何成功找出需要帮助的人群并引导他们的行为向好的方向发展，这一点更加无法确定。

【点拨】1)steer“控制，引导”。2)virtuous“品行端正的，正直的”。