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é????¨??·????o??°??¤????è???¤?????12??????é??è????¤??¨é????¨???é??è??è?????????o???'?????¤??????è????¤?°?é????o2.0m/s,???è????¤é???§????10000/3600 / 2 = 1.38m2???é???????????????????????è????¤???????????·????°??°??¤????è???¤??12??????é??è????¤??¨????¤???????????????¨???é??????????????A3é??????o§???????21???é?2è??????????¤?????o????±?????????¨???èo?????????o?°?è????¤??¨???100mm???????????????è|?????????????????o¤??'????????????