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nsearchssearch 0371-60107537ssearcha0371-60107537c0第一节：任务型读写（共10小题；每小题1分，满分10分）
阅读下面短文，根据所读内容在表格中的空白处填入恰当的单词。注意：每个空格只填一个单词。
Attention deficit（不足）hyperactivity（活动过度）disorder is known by the letters A．D．H D．Children with A．D．H．D．might have trouble paying attention．They might not seem to listen and might forget things．They might not be able to stay seated or play quietly．They might talk too much and act and speak without thinking about the results of their behavior．These are among the signs named on the web site of America’s Centers for Disease Control and Prevention．
Doctors usually identify the disorder in children．But experts say the behaviors often last into adulthood．Researchers have been looking for the cause or causes of attention deficit hyperactivity disorder．Now, a brain-imaging study offers more evidence that could lead to new ways to treat it．Researchers say they observed shortages in the brain's reward system in patients with A．D．H．D．The study found that levels of some proteins were lower than normal．Nora Volkow, director of the National Institute on Drug Abuse, says the lack of attention and self –control that mark A.B.H.D. could be caused by problem in the flow of dopamine（多巴胺）. She says people might have difficulty completing an activity if they cannot expect some kind of reward in return. Researchers studied the pathways on which dopamine travels and A.D.H.D. Doctor Volkow says the researchers then compared the pathways to those of 44 adults without the disorder. “There was a lower concentration of dopamine markers in the brain of individuals with A.D.H.D., specifically in the areas of the brain that are involved with reward and motivation. And the dopamine levels were directly linked to the severity, of the patient’s inattention she says.”
The study used brain images taken at Brookhaven National Laboratory in new York State. Gene-Jack Wang is chairman of the Brookdhaven medical department. He says the finding might also help explain why people with A.D.H.D.