2014 完形填空

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.