简述采用面向对象方法进行系统分析的主要工作。
从功能需求出发，分析识别出对象，将相同的数据类型抽象为独立的同类模块。
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Youcanreceiveaspecial15%discountonordersplacebeforetheendofDecember.
Intheearlieststagesofman'sdevelopmenthehadnomoreneedofmoneythananimalshave.Hewascontentwithverysimpleformsofshelter,madehisownroughtoolsandweaponsandcouldprovidefoodandclothingforhimselfandhisfamilyfromnaturalmaterialsaroundhim.Ashebecamemorecivilized,however,hebegantowantbettershelter,moreefficienttoolsandweapons,andmorecomfortableandmorelastingclothingthancouldbeprovidedbyhisownneighborhoodorbytheworkofhisownunskilledhands.Forthesethingshehadtoturntotheskilledpeoplesuchassmiths,leatherworkersorcarpenters.Itwasthenthatthequestionofpaymentarose.
Atfirsthegotwhathewantedbyasimpleprocessofexchange.Thesmithwhohadnotthetimetolookafterlandorcattlewasgladtotakemeatorgrainfromthefarmerinexchangeforanaxeoraplough.Butasmoreandmoregoodswhichhadnofixedexchangevaluecameonthemarket,exchangebecametoocomplicatedtobesatisfactory.Anotherproblemarosewhenthosewhomadethingswantedtogetstocksofwoodorleather,oriron,buthadnothingtoofferinexchangeuntiltheirfinishedgoodswereready.Thusthedifficultiesofexchangeledbydegreestotheinventionofmoney.Insomecountrieseasilyhandledthingslikeseedsorshellsweregivenacertainvalueandthefarmer,insteadofpayingthesmithforanewaxebygivinghimsomemeatorgrain,gavehimsomanyshells.Ifthesmithhadanyshellsleftwhenhehadboughthisfood,hecouldgetstocksoftherawmaterialsofhistrade.Insomecountriesquitelargethingssuchascowsorcamelsorevenbigflatstoneswereusedfortrade.Later,piecesofmetal,bearingvaluesaccordingtotherarityofthemetalandthesizeofthepieces,orcoinswereused.Moneyasweknowithadarrived.
1.Exchangeofgoodsbecamedifficultbecause_________.
Amanbecamemorecivilized
Bsmithsbegantolookafterlandorcattleintheirsparetime
Cmoreandmoregoodswhichhadnofixedexchangealuescametothemarker
Dfarmershadn'tenoughgrainormeattoprovidefor
skilledworkers
2.Moneywasnotuseduntil_______.
Apaperwasinvented
Bpeoplepracticedasimpleprocessofexchange
CnothingcouldbeofferedinexchangeDtheexchangeofonethingforanotherbecametoocomplicated
3.Thebesttitleforthispassageis_____.
AWhatismoney
BWhataremoney'sfunctions.
CTheimportanceofmoney
DThebeginningofmoney
Managersknowthatstressisabarriertomotivatingtheworkforce.
SASemploysafull-timeergonomicsspecialisttoselectofficefurniturethatwillreducephysicalstressandstrain.
Wearepreparetoofferourcomputerstoyouatthespecialdiscountrateof15%.
