Ourbrainisprobablythemostimportantorganinourbody．It's（61）incrediblycomplexthingthathelps（62）think，speak，feelandmove．It'snowonderweneedtolookafteritandjustliketherestofourbody，weneedtokeepit

Question

Our brain is probably the most important organ in our body．It's（61）___incredibly complex thing that helps （62）___think，speak，feel and move．It's no wonder we need to look after it and just like the rest of our body，we need to keep it exercised to keep it healthy．Our brain（63）___ （make） up of 86 billion neurons-or nerve cells-but as we get （64）___（old） some of these（65）___（slow） die off．In extreme cases，nerve cells in different （66）___（area） of the brain become damaged and eventually die（67）___（cause） a condition called dementia （68）___ a person is unable to perform certain mental functions．It's a good idea（69）___（train） our brain by learning ways to increase our memory or intelligence．I like to stretch my brain by doing a crossword or a Sudoku puzzle．There's also evidence that learning a（70）___（two） language can boost your brainpower．

Answer 1

1．an；考查冠词．句中thing表示泛指，要用不定冠词来限定．       
2．us；考查代词．句意指代的是我们，且在句中作helps的宾语，要用人称代词的宾格．        
3．is made；考查被动语态．be made up of由什么组成；句意表达的是客观事实，要用一般现在时态的被动语态．
4．older；考查比较级．句意表达的是暗含比较，要用比较级，即我们一天天变老；句中old作系动词get的表语，要用形容词的比较级形式．     
5．slowly；考查副词．句中slow修饰动词die off，要用副词形式．  
6．areas；考查名词．句意表达的是大脑有不同的区域，名词要用复数．   
7．causing；考查分词．句中cause作结果状语，要用非谓语动词；cause与前面的这个句子表达的事情构成主谓关系，要用表示主动的现在分词．    
8．where；考查连词．句中a person is unable to perform certain mental functions修饰dementia，是一个定语从句；从句结构完整，要用关系副词；先行词dementia表示抽象地点，要用where来引导．     
9．to train；考查句型搭配．it is+名词+to do sth做某事是怎样的，it充当形式主语，真正的主语是后面的动词不定式．    
10．second；考查数词．句中two修饰名词language，表示第二语言，要用序数词来表示．