巨鹿之战后，六国再也无力抵御秦国的攻势；秦朝为了抵御匈奴的进攻，修建了西起临洮，东到山海关的万里长城。   

（1）错误：                                                                                                                                 

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（2）错误：                                                                                                                                

         理由：                                                                                                                                

呼吸的频率与深浅对肺通气量影响很大。