据考古发现,我国陕西省半坡原始村落建在河谷阶地上,图甲为半坡原始村落复原模型,图乙为河谷阶地示意图。半坡原始村落选择建在河谷阶地上,考虑的主要因素有() ①接近水源 ②安全防卫 ③对外联系便利 ④地势较高,免受洪涝之害
A. ①②③
B. ②③④
C. ①③④
D. ①②④
Questions11to15arebasedonthefollowingpassage.Scratchythroats,stuffynosesandbodyachesallspellmisery,butbeingabletotellifthecauseisacoldorflu(流感)maymakeadifferenceinhowlongthemiserylasts.TheAmericanLungAssociation(ALA)hasissuednewguidelinesoncombatingcoldsandtheflu,andoneofthekeysisbeingabletoquicklytellthetwoapart.That’sbecausetheprescriptiondrugsavailableforthefluneedtobetakensoonaftertheillnesssetsin.Asforcolds,thesoonerapersonstartstakingover-the-counterremedy,thesoonerreliefwillcome.Thecommoncoldandthefluarebothcausedbyviruses.Morethan200virusescancausecoldsymptoms,whilethefluiscausedbythreeviruses—fluA,BandC.Thereisnocureforeitherillness,buttheflucanbepreventedbythefluvaccine(疫苗),whichis,formostpeople,thebestwaytofighttheflu,accordingtotheALA.Butifthefludoesstrike,quickactioncanhelp.Althoughthefluandcommoncoldhavemanysimilarities,therearesomeobvioussignstolookfor.Coldsymptomssuchasstuffynose,runnynoseandscratchythroattypicallydevelopgradually,andadultsandteensoftendonotgetafever.Ontheotherhand,feverisoneofthecharacteristicfeaturesofthefluforallages.Andingeneral,flusymptomsincludingfeverandchills,sorethroatandbodyachescomeonsuddenlyandaremoreseverethancoldsymptoms.TheALAnotesthatitmaybeparticularlydifficulttotellwheninfantsandpreschoolagechildrenhavetheflu.Itadvisesparentstocallthedoctoriftheirsmallchildrenhaveflu-likesymptoms.Bothcoldandflusymptomscanbeeasedwithover-the-countermedicationsaswell.However,childrenandteenswithacoldorflushouldnottakeaspirinforpainreliefbecauseoftheriskofReyesyndrome(综合症),ararebutseriousconditionoftheliverandcentralnervoussystem.Thereis,ofcourse,novaccineforthecommoncold.Butfrequenthandwashingandavoidingclosecontactwithpeoplewhohavecoldscanreducethelikelihoodofcatchingone.Ifchildrenhaveflu-likesymptoms,theirparents()
A. areadvisednottogivethemaspirin
B. shouldwatchoutforsignsofReyesyndrome
C. areencouragedtotakethemtohospitalforvaccination
D. shouldpreventthemfrommixingwithpeoplerunningafever