As many people hit middle age,they often start to notice that their memory and mental clarity are not what they used to be.We suddenly can’t remember___1___we put the keys just a moment ago,or an old acquaintance’s name,or the name of an old band we used to love.As the brain___2___,we refer to these occurrences as“senior moments.”___3___seemingly innocent,this loss of mental focus can potentially have a（n）___4___impact on our professional,social,and personal___5___.Neuroscientists,experts who study the nervous system,are increasingly showing that there’s actually a lot that can be done.It___6___out that the brain needs exercise in much the same way our muscles do,and the right mental___7___can significantly improve our basic cognitive___8___.Thinking is essentially a___9___of making connections in the brain.To a certain extent,our ability to___10___in making the connections that drive intelligence is inherited.___11___,because these connections are made through effort and practice,scientists believe that intelligence can expand and fluctuate___12___mental effort.Now,a new Web-based company has taken it a step___13___and developed the first“brain training program”designed to actually help people improve and regain their mental___14___.The Web-based program___15___you to systematically improve your memory and attention skills.The program keeps___16___of your progress and provides detailed feedback___17___your performance and improvement.Most importantly,it___18___modifies and enhances the games you play to___19___on the strengths you are developing—much like a（n）___20___exercise routine requires you to increase resistance and vary your muscle use.（12）选？
上下文逻辑关系+介词短语辨析首先，由该句前半句“构建这些连接需要通过努力和实践”可知，锻炼是智力提高的原因。其次，mental effort和前面的effort and practice形成了照应的关系，所以构建连接依靠于effort，而智力又依靠于构建连接。此外，根据四个选项的具体含义，可推知according to最符合句意，因此，正确答案为D。选项A和B表示“智力增加”和“锻炼”之间毫无关系，与文意不符，可排除。选项C表明“除了锻炼（还有其他）或者除了锻炼（别无其他）”，语气太绝对，不符合句意，可排除。
