管电流的改变,一般是

A、调节灯丝初级电路中的电阻
B、调节电源电压
C、调节稳压器的输入电压
D、调节稳压器的输出电压
E、调节管电压
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正确答案:

A

答案解析:

暂无解析

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As____clearfromhismanners,heisateacher.

A、being
B、is
C、tobe
D、been

PARTVREADINGCOMPREHENSION

PASSAGEONE

(1)TheearliestsettlerscametotheNorthAmericancontinenttoestablishcoloniesthatwerefreefromthecontrolsthatexistedinEuropeansocieties.Theywantedtoescapethecontrolsplacedontheirlivesbykingsandgovernments,priestsandchurches,noblemenandaristocrats.ThehistoricdecisionsmadebythosefirstsettlershavehadaprofoundeffectontheshapingoftheAmerican

character.Bylimitingthepowerofthegovernmentandthechurchesandeliminatingaformalaristocracy,theycreatedaclimateoffreedomwheretheemphasiswasontheindividual.IndividualfreedomisprobablythemostbasicofalltheAmericanvalues.Byfreedom,Americansmeanthedesireandtheabilityofallindividualstocontroltheirowndestinywithoutoutsideinterferencefromthegovernment,arulingnobleclass,thechurch,oranyotherorganizedauthority.

(2)Thereis,however,apricetobepaidforthisindividualfreedom:self-reliance.ItmeansthatAmericansbelievetheyshouldstandontheirownfeet,achievingbothfinancialandemotionalindependencefromtheirparentsasearlyaspossible,usuallybyage18or21.

(3)AsecondimportantreasonwhyimmigrantshavetraditionallybeendrawntotheUnitedStatesisthebeliefthateveryonehasaequalchancetoenteraraceandsucceedinthegame.BecausetitlesofnobilitywereforbiddenintheConstitution,noformalclasssystemdevelopedintheU.S.

(4)Thereis,however,apricetobepaidforthisequalityofopportunity:competition.Ifmuchoflifeisseenasrace,thenapersonmustruntheraceinordertosucceed;apersonmustcompetewithothers.ThepressuresofcompetitioninthelifeofanAmericanbegininchildhoodandcontinueuntilretirementfromwork.Infact,anygroupofpeoplewhodoesnotcompetesuccessfullydoesnotfit

intothemainstreamofAmericanlifeaswellasthosewhodo.

(5)AthirdreasonwhyimmigrantshavetraditionallycometotheUnitedStatesistohaveabetterlife.Becauseofitsabundantnaturalresources,theUnitedStatesappearedtobea“landofplentywheremillionscouldcometoseektheirfortunes.Thephrase“goingfromragstoriches”becameasloganfortheAmericandream.Manypeopledidachievematerialsuccess.MaterialwealthbecameavaluetotheAmericanpeople,anditalsobecameanacceptedmeasureofsocialstatus.

(6)Americanspayaprice,however,fortheirmaterialwealth:hardwork.HardworkhasbeenbothnecessaryandrewardingformostAmericansthroughouttheirhistory.Insomeways,materialpossessionsareseenasevidenceofpeople’sabilities.BarryGoldwater,acandidateforthepresidencyin1964,saidthatmostpoorpeoplearepoorbecausetheydeservetobe.MostAmericanswouldfind

thisaharshstatement,butmanymightthinktherewassometruthinit.

(7)ThesebasicvaluesdonottellthewholestoryoftheAmericancharacter.Rather,theyshouldbethoughtofasthemes,aswecontinuetoexploremorefacetsoftheAmericancharacterandhowitaffectslifeintheUnitedStates.

1.Para.4seemstosuggestthat__________.

A.Americansarebornwithasenseofcompetition

B.thepressureofcompetitionbeginswhenonestartswork

C.successfulcompetitionisessentialinAmericansociety

D.competitionresultsinequalityofopportunities

2.WhichofthefollowingmethodsdoestheauthormainlyuseinexplainingAmericanvalues?

A.Comparison

D.Causeandeffect

C.Definition

D.Processanalysis

Oneoftherequirementsforafireisthatthematerial____toitsburningtemperature.

A、beheated
B、isheated
C、wouldbeheated
D、toheated

Thematterisnottobe____.

A、watchedfor
B、waitedon
C、takenover
D、trifledwith

Manyartistspredictthatthisbrilliantyoungactor__tobeashinningstar.

A、destines
B、willbedestined
C、isdestined
D、hasbeendestined
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