某反馈放大电路的方框图如图所示,试推导其闭环增益xo/xi的表达式。
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PartIReadingComprehension
Passage1
Questions1to5arebasedonthefollowingpassage:
InWashingtonD.C.,1600PennsylvaniaAvenueisaveryspecialaddress.ItistheaddressoftheWhiteHouse,thehomeofthepresidentoftheUnitedStates.
OriginallytheWhiteHousewasgrayandwascalledthePresidentialPalace.Itwasbuiltfrom1792to1800.atthistime,thecityofWashingtonitselfwasbeingbuilt;itwastobethenation’snewcapitalcity.GeorgeWashington,thefirstpresident,andPierreCharlesL’Enfant,aFrenchengineer,chosetheplaceforthenewcity.L’Enfantthenplannedtheycity.Thepresident’shomewasanimportantpartoftheplan.
Acontestwasheldtopickadesignforthepresident’shome.AnarchitectnamedJamesHobanwon.Hedesignedalargethree-storyhouseofgraystone.
PresidentWashingtonneverlivedinthePresidentPalace.ThefirstpresidenttolivetherewasJohnAdams,thesecondpresidentoftheUnitedStates,andhiswifeMrs.Adamsdidnotreallylikehewnewhouse.Inherletters,sheoftencomplainedaboutthecold.Fiftyfireplaceswerenotenoughtokeepthehousewarm!
In1812theUnitedStatesandBritainwenttowar.In1814theBritishinvadedWashington.Theuburnedmanybuildings,includingthePresidentialPalace.
AfterthewarJamesHoban,theoriginalarchitect,partiallyrebuiltthepresident’shomes.Tocoverthemarksofthefire,thebuildingwaspaintedwhite.BeforelongitbecameknownastheWhiteHouse.
TheWhiteHouseisoneofthemostpopulartouristattractionsintheUnitedStates.Everyyearmorethan1.5millionvisitorsgothroughthefiveroomsthatareopentothepublic.
1.TheWhiteHousewasbuiltinWashington.
A.becauseaFrenchengineerwasinvitedtodesignit
B.becausePresidentGeorgeWashingtonlikedtoliveinit
C.becausetheBritishinvaderslivedinitin1812-1814
D.becauseitwastobethenation’scapitalcity
2.ThePresidentialPalacewas.
A.paintedgrayandwhiteB.madeofgraystone
C.madeofwhitestoneD.madeverywarminwinter
3.Thepresident’shomeandthecityofWashingtonwere.
A.builtbytheAmericanarmyB.builtbytheBritishtroops
C.plannedbyGeorgeWashingtonD.plannedbytheFrench
4.Theoriginalhomeofthepresidentneededtoberebuilt.
A.becauseJohnAdam’swifedidnotlikeit
B.becauseitwascoldinwinterevenwith50fireplaces
C.becauseithadburneddownduringthewar
D.becauseGeorgeWashingtonwasnotwillingtoliveinit
5.Thenewpresidentialhomewaspaintedwhiteto.
A.coverthemarksoffireB.attracttouristfromFrance
C.topleaseMrs.JohnAdamsD.keepitwarminwinter
接产要领不包括下列哪项
PartIVTranslation:
Almost30millionAmericansweightatleast20percentmorethantheiridealweight.Infact,theUnitedStateisthemostoverweightcountryinthewild.(PassageThree)
PartIVTranslation
Satellitemassagershavethesameglobalcoverageassatellitetelephones,butcarrytextalone,whichcouldbeusefulforthosewithlaptopcomputers.(PassageFour)
产程中胎心监护,下列哪项是错误的