[解析]
(1)细节理解题。根据第二段中Moreover,for those who struggle to fall asleep at night,habitual morning exercise may help to reset their circadian rhythms,the internal,biological processes that regulate the24﹣hour sleep﹣wake cycle.(此外,对于那些晚上难以入睡的人来说,习惯性晨练可能有助于重置他们的昼夜节律,这是调节24小时睡眠﹣觉醒周期的内部生物过程。)可知,对于有睡眠障碍的人来说,规律的晨间锻炼有助于调节睡眠。故选B。
(2)细节理解题。根据第三段中A small,12﹣week study focusing on pre﹣diabetic and diabetic men found that afternoon training produced slightly more beneficial metabolic(新陈代谢的)effects and resulted in a little more fat loss compared to morning training.(一项针对糖尿病前期和糖尿病男性的为期12周的小型研究发现,与上午训练相比,下午训练产生的有益代谢效果略多,脂肪减少量略多。)可知,对糖尿病人来说下午锻炼可能更有效。故选D。
(3)推理判断题。根据最后一段中Whether morning,afternoon,or evening,it is optimal(最佳的)if exercise timing remains somewhat consistent,research has found.(研究发现,无论是早上、下午还是晚上,如果锻炼时间保持一定程度的一致,则是最佳的。)可知,每天的锻炼时间保持一致是较为推荐的。故选C。
(4)标题归纳题。根据第一段A key part of starting to exercise is choosing when to work out.Morning,afternoon,or evening:Which time is best?Scientists have studied this dilemma extensively.(开始锻炼的一个关键部分是选择何时锻炼。上午、下午或晚上:哪个时间最好?科学家们对这一困境进行了广泛的研究。)可知,文章主要谈论的话题为:什么时间锻炼更好?因此本文的最佳标题是B.AM or PM:When is the best time to exercise?(上午或下午:锻炼的最佳时间是什么时候?)。故选B。