Insomniacs(someone who cannot sleep easily)don't just suffer at night. During the day, they often feel sleepy, have trouble concentrating and report greater difficulty with work or school performance than individuals who get adequate sleep. But researchers are intrigued by an apparent【C1】______: Despite what insomnia patients experience subjectively, they often seem able to【C2】______cognitive tasks as well as people getting adequate sleep. One【C3】______is that insomnia doesn't lead to【C4】______performance after all—maybe it just feels that way. Using brain imaging technology, researchers【C5】______25 people with insomnia and 25 normal sleepers as they performed an eight-minute working-memory task【C6】______the processing and storing of short-term memory. As the exercises became more difficult, the people who sleep【C7】______had increased activity in parts of the brain【C8】______the insomnia subjects didn't. And the poor sleepers couldn't turn off the brain's "mind wandering" regions, also known as the "【C9】______mode" network, located generally【C10】______the brain's midline. These regions are ordinarily active when a person isn't【C11】______in goal-directed behavior and they are【C12】______when the person switches to a task. The more the insomnia patients subjectively reported【C13】______and difficulty concentrating, and the【C14】______they subjectively reported performing their task, the greater was their【C15】______to turn off the mind wandering regions, as measured by the MRI. "There's no doubt that what's going on in the brain could be measured as less【C16】______," experts said. More research is needed to understand how insomnia patients were able to【C17】______and perform the tasks equally well despite the apparent【C18】______in brain activity. The ultimate goal of this kind of research is to【C19】______the environmental and genetic causes of insomnia and develop【C20】______treatments.
【答案解析】解析：空格处现在分词对task的具体内容进行说明，空格后的the processing and storing of short-term memory是task所包括的内容。故选C项involving“包括，涉及”。
单选题
【C7】
【正确答案】
B
【答案解析】解析：本句中，研究者对两组受试者进行测试，the people who sleep——和the insomnia subjects是两个并列句的主语。两者要有“对照”作用，因此在语义上应相对，与the insomnia subjects(患失眠症的实验对象)对应的应为睡眠正常的人，故选B项soundly“酣畅地”。
单选题
【C8】
【正确答案】
A
【答案解析】解析：空格前提到the people who…had increased activity…，而空格后为the insomnia subjects didn’t，两者之间的逻辑关系是转折，A项while“而，然而”符合要求。
单选题
【C9】
【正确答案】
B
【答案解析】解析：文中also known as提示此处the“______mode”network与上文提及的the brain’s“mind wandering”regions指同一个事物。因此，答案应为与“mind wandering”regions(”心不在焉”区)相关联的default mode(出错模式)，故选B。
【答案解析】解析：比较When a person isn’t——in goal-directed behavior和when the person switches to a task，我们发现这两句的结构是类似的，goal-directed behavior和task为近义表达。而且后面的switch to有“转向”的意思，这说明前面是没有做一些有目的性的行为。故选D项，be engaged in意为“从事”。
【答案解析】解析：本文第1段第2句提到失眠症患者的感觉：很难集中精神、感到困。本句中的difficulty concentrating与第1段的have trouble concentrating对应，因此空格处应跟they often feel sleepy对应，故选B项sleepiness“嗜睡”。
单选题
【C14】
【正确答案】
D
【答案解析】解析：本文第1段第2句中they feel sleepy,have trouble concentrating and report greater difficulty with work提示，失眠症患者完成任务的情况应是“更差”，故选D项worse。
单选题
【C15】
【正确答案】
A
【答案解析】解析：本句和上两句构成“the+比较级”的结构。此处句意为“他们关掉焉区域的——会更强”。结合本文第5段第2句中的the poor sleepers couldn't turn off the brain's“mindwandering”regions(睡眠差的人则无法关闭大脑的“心不在焉”区)，可推断，睡眠不好者无力关掉“心不在焉”区。故选A项inability“无能，无力”。
单选题
【C16】
【正确答案】
C
【答案解析】解析：本题所在句子是对上文所提失眠症患者的各种表现的总结。依据上文的各种提示，如：他们经常感觉很困、很难集中精力、工作或学校表现中遇到更大的困难(第1段)，睡眠不好者不能关闭“心不在焉”区(第5段)，可推断他们“效率不高”，be less efficient“效率不高”，故选C项efficient。