[解析]
(1)推理判断题。根据第一段Adolescent mental health has been declining for years,and an increasing amount of research suggests that social media platforms could be partially to blame.(多年来,青少年的心理健康状况一直在下降,越来越多的研究表明,社交媒体平台可能是部分原因);第二段Numerous studies demonstrate that adolescent rates of depression,anxiety and loneliness have skyrocketed in the U.S.and elsewhere since around the time that smartphones and social media became ever﹣present.(大量研究表明,自从智能手机和社交媒体无处不在以来,美国和其他地方的青少年抑郁、焦虑和孤独的比例急剧上升。)可知,社交媒体对青少年心理健康有负面影响。故选A项。
(2)观点态度题。根据第三段They concluded that social media us was associated with a slight increase in depression and anxiety but also improvements in feelings of belonging and connectedness.(他们得出结论,社交媒体与抑郁和焦虑的轻微增加有关,但也与归属感和联系感的改善有关)可知,Jeff Hancock对社交媒体的态度是客观的。A.Critical.批评的;B.Objective.客观的;C.Favorable.支持的;D.Indifferent.不在乎的。故选B项。
(3)推理判断题。根据第四段Makarin says much of the harm they documented came from social comparisons:students viewed the online profiles of their peers and believed them to "have nicer lives,party more often,have more friends and look better.( Makarin说,他们记录的大部分危害来自社会比较:学生们在网上查看同龄人的资料,认为他们"生活得更好,聚会更频繁,朋友更多,看起来更好)可知,Makarin认为,社交媒体让他们觉得自己比别人差,这对青少年的心理健康不利。故选D项。
(4)目的意图题。根据第一段Adolescent mental health has been declining for years,and an increasing amount of research suggests that social media platforms could be partially to blame.But experts continue to debate just how much impact they have.(多年来,青少年的心理健康状况一直在下降,越来越多的研究表明,社交媒体平台可能是部分原因。但专家们仍在争论它们到底有多大的影响。)以及下文的说明可知,短文的目的是展示社交媒体与心理健康之间联系的研究结果。故选C项。