With time flying, people become aged. Then many people even in their middle age 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 friend'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__ effect on our social and __5__ well­being.

　　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 (认知的) __8__. Thinking is basically a __9__ of making connections in the brain. To a certain extent, our ability to __10__ in making connections that drive intelligence is inherited (继承的). __11__， because these connections are made through effort and practice, scientists believe that intelligence can expand and wave __12__ mental effort.

　　Now, a new web­based company has taken a step __13__ and developed the first "brain training program" designed to actually help people improve and __14__ their mental sharpness.

　　The web­based program __15__ you to systematically improve your memory and attention skills. The program keeps a(n) __16__ of your progress and provides detailed feedback (反馈意见) about your performance and __17__. Most importantly, it __18__ changes and improves the games you play to __19__ the strength you are developing - much like a(n) __20__ exercise routine which requires you to increase resistance and vary your muscle use.

　　语篇解读：有一个公司开发了一种"大脑培训课程"，以帮助人们预防记忆衰退。

　　1．A.where　　　　　　 　B．when

　　C．that D．why

　　解析：选A　联系空后的"we put the keys just a moment ago"可知，此处指记不清刚刚把钥匙放在哪里(where)了。

　　2．A.improves B．fades

　　C．recovers D．falls

　　解析：选B　从空后的"we refer to these occurrences as 'senior moments'"可知，随着大脑衰老，我们会出现忘事、糊涂等尊长表现。fade"(身体)变得虚弱"。

　　3．A.If B．Unless

　　C．Once D．While

　　解析：选D　结合空后的"seemingly innocent, this loss of mental focus can potentially have"可知，此处用While表前后文的转折关系。

4．A.irregular B．limited