[解析]
(1)推理判断题。由本文第二段Recommended levels of exercise in the United States,according to the US Centers for Disease Control and Prevention (CDC),include aerobic (有氧的) activity at proper levels for 2.5 hours a week,along with a workout of all major muscle groups twice a week.Or,a person can choose a high﹣level aerobic exercise,such as running,for 1.25 hours each week,along with the same amount of strength training.(根据美国疾病控制与预防中心(CDC)的建议,美国人的运动水平包括每周2.5小时的适当水平的有氧运动,以及每周两次对所有主要肌肉群的锻炼。或者,一个人可以选择高水平的有氧运动,比如跑步,每周1.25小时,同时进行同样数量的力量训练。)可知引用的数字都是在关键词"include"之后作为具体例子,例子是为了进一步解释前文内容"Recommended levels of exercise in the United States",所以第二段引用数字是为了建议适当程度的锻炼。故选B。
(2)词句猜测题。由本文第三段Middle﹣to﹣high﹣level exercise is good for us,according to the CDC.It improves sleep,lowers blood pressure,protects against heart disease and diabetes,reduces stress,improves mood,and fights anxiety and depression.But in today's busy world,many people find it difficult to fit in a jog or a visit to the gym. (根据美国疾病控制与预防中心的说法,中高水平的运动对我们有益。它能改善睡眠,降低血压,预防心脏病和糖尿病,减轻压力,改善情绪,对抗焦虑和抑郁。但是在当今繁忙的世界里,许多人发现很难抽出时间去慢跑或去健身房。)可知,作者想要强调的是转折词"but"后的内容,即虽然运动有众多好处,但是人们因为繁忙或压力很难去适应一些运动。由此推知,划线部分的意思是"患有抑郁的人,更不愿意锻炼",A.Running may possibly add to depression.跑步可能会增加抑郁;B.People tend to exercise more when depressed.人们在抑郁时倾向于多运动;C.Depressed people are less willing to exercise.抑郁的人不太愿意锻炼;D.Working out regularly helps increase motivation.定期锻炼有助于提高动力。故选C。
(3)细节理解题。由本文第六段The benefits were strongest when a person changed from being a couch potato to adding movement to the day,the study said.(研究称,当一个人从"沙发土豆"变成每天运动时,这种好处是最大的。)可知懒散的人可以从锻炼中获益良多,故选D。
(4)推理判断题。由本文最后一段"Even just walking three times a week seems to give people better mental health than not exercising at all," said study author Adam Chekroud,an assistant professor of psychiatry at Yale University.(该研究的作者、耶鲁大学精神病学助理教授亚当•切克鲁德说:"即使每周只散步三次,似乎也比完全不运动更能让人保持心理健康。")可知,亚当•切克罗德主张人们要去锻炼,哪怕仅仅是散步都比人们什么也不做强。所以B.Half a loaf is better than no bread.(半个面包总比没有面包好。)符合亚当•切克罗德对锻炼的观点。故选B。