[解析]
(1)细节理解题。根据第一段A new study discovers that sharks do sleep,and they often sleep with their eyes open.Since some sharks have to swim constantly to keep oxygen﹣rich water flowing over their gills (鱼鳃),people have long thought that they don't sleep at all.(一项新的研究发现,鲨鱼确实会睡觉,而且它们经常睁着眼睛睡觉。由于一些鲨鱼必须不停地游泳,以保持富含氧气的水流过它们的鳃,人们一直认为它们根本不睡觉。)可知之前关于鲨鱼的误解是他们总是醒着,故选D。
(2)细节理解题。根据第三段中的At night,they tended to keep their eyes open more often,leading researchers to suspect that the sharks' eye closure might have more to do with light than the sleep state itself. (在晚上,它们往往会更频繁地睁开眼睛,这使得研究人员怀疑鲨鱼闭上眼睛可能更多地与光线有关,而不是睡眠状态本身。)可知吃水板鲨闭上眼睛可能不是为了睡觉,而是为了避光。故选D。
(3)段落大意题。根据第四段中的Understanding how and why these animals sleep will provide important understanding into the function of sleep and how the animal has evolved over time.(了解这些动物如何以及为什么睡觉,将为了解睡眠的功能以及动物如何随着时间的推移而进化提供重要的帮助。)可知第四段主要讲的是研究的意义。故选C。
(4)推理判断题。根据最后一段The team points out that more research will be needed to see if other species sleep like the draughtsboard sharks.Next they plan to continue to analyze the sharks' brain activity while they sleep,to learn more about their waking and resting states.(研究小组指出,还需要更多的研究来看看其他物种是否像吃水板鲨那样睡觉。下一步,他们计划继续分析鲨鱼睡觉时的大脑活动,以更多地了解它们醒着和休息时的状态。)可推测研究小组认为他们在最后一段的研究不够充分。故选A。