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储存条件、防护措施、卫生环境
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Nearlyallthefamiliescanmanagetomeetthesoaringtuitioncoststhroughvariousinvestmentplans.
_____theirhelp,wewouldnothavesucceeded.
I’mworriedabouttheappearanceofthefloor.Ineedto_____it.
Wecanbeginourdiscussionof“populationasglobalissue”withwhatmostpersonsmeanwhentheydiscuss“thepopulationproblem”:toomanypeopleonearthandatoorapidincreaseinthenumberaddedeachyear.Thefactsarenotindispute,Itwasquiterighttoemploytheanalogythatlikeneddemographicgrowthto“along,thinpowderfusethatburnssteadilyandhaltinglyuntilitfinallyreachesthechargeandexplodes.”
Tounderstandthecurrentsituation,whichischaracterizedbyrapidincreasesinpopulation,itisnecessarytounderstandthehistoryofpopulationtrends.Rapidgrowthisacomparativelyrecentphenomenon.Lookingbackatthe8,000yearsofdemographichistory,wefindthatpopulationshavebeenvirtuallystableorgrowingveryslightlyformostofhumanhistory.Formostofourancestors,lifewashard,oftennasty,andveryshort.Therewashighfertilityinmostplaces,butthiswasusuallybalancedbyhighmortality.Formostofhumanhistory,itwasseldomthecasethatoneintenpersonswouldlivepastforty,whileinfancyandchildhoodwereespeciallyriskyperiods.Often,societieswereincleardangerofextinctionbecausedeathratescouldexceedtheirbirthrates.Thus,thepopulationproblemthroughoutmostofhistorywashowtopreventextinctionofthehumanrace.
Thispatternisimportanttonotice.Notonlydoesitputthecurrentproblemsofdemographicgrowthintoahistoricalperspective,butitsuggeststhatthecauseofrapidincreaseinpopulationinrecentyearsisnotasuddenenthusiasmformorechildren,butanimprovementintheconditionsthattraditionallyhavecausedhighmortality.
Demographichistorycanbedividedintotwomajorperiods:atimeoflong,slowgrowthwhichextendedfromabout8,000BC.tillapproximatelyAD.1650.Inthefirstperiodofsome9600years,thepopulationincreasedfromsome8millionto500millionin1650.Between1650andthepresent,thepopulationhasincreasedfrom500milliontomorethan4billion.Anditisestimatedthatbytheyear2000therewillbe6.2billionpeoplethroughouttheworld.Onewaytoappreciatethisdramaticdifferenceinsuchabstractnumbersistoreducethetimeframetosomethingthatismoremanageable.Between8000BCand1650,anaverageofonly50,000personswasbeingaddedannuallytotheworld’spopulationeachyear.Atpresent,thisnumberisaddedeverysixhours.Theincreaseisabout80,000,000personsannually.
1.Whichofthefollowingdemographicgrowthpatternismostsuitableforthelongthinpowderfuseanalogy?
A.Avirtuallystableorslightlydecreasingperiodandthenasuddenexplosionofpopulation.
B.Aslowgrowthforalongtimeandthenaperiodofrapid,dramaticincrease.
C.Toomanypeopleonearthandafewrapidincreaseinthenumberaddedeachyear.
D.Alongperiodwhendeathratesexceedsbirthratesandthenashortperiodwithhigherfertilityandlowermortality.
2.Duringthefirstperiodofdemographichistory,societieswereoftenindangerofextinctionbecause___.
A.onlyoneintenpersonscouldlivepast40.
B.therewashighermortalitythanfertilityinmostplaces.
C.itwastoodangeroustohavebabiesduetothepoorconditions.
D.ourancestorshadlittleenthusiasmformorechildren.
3.Whichstatementistrueaboutpopulationincrease?
A.Theremightbeanincreaseof2.2billionpersonsfromnowtotheyear2000.
B.About50,000babiesareborneverysixhoursatpresent.
C.Between8000BCandthepresent,thepopulationincreaseisabout80,000,000personseachyear.
D.Thepopulationincreasedfasterbetween8000BCand1650thanbetween1650andthepresent.
4.Theauthorofthepassageintendsto___.
A.warnpeopleagainstthepopulationexplosioninthenearfuture.
B.comparethedemographicgrowthpatterninthepastwiththatafter1650.
C.findoutthecauseforrapidincreaseinpopulationinrecentyears.
D.presentusaclearandcompletepictureofthedemographicgrowth.
5.Theword“demographic”inthefirstparagraphmeans___.
A.statisticsofhuman.
B.surroundingsstudy.
C.accumulationofhuman.
D.developmentofhuman.
Withoutregularsuppliesofsomehormonesourcapacitytobehavewouldbeseriouslyimpaired;withoutotherswewouldsoondie.Tinyamountsofsomehormonescanmodifymoodsandactions,ourinclinationtoeatordrink,ouraggressivenessorsubmissiveness,andourreproductiveandparentalbehavior.Andhormonesdomorethaninfluenceadultbehavior;earlyinlifetheyhelptodeterminethedevelopmentofbodilyformandmayevendetermineanindividual’sbehavioralcapacities.Laterinlifethechangingoutputsofsomeendocrineglandsandthebody’schangingsensitivitytosomehormonesareessentialaspectsofthephenomenaofaging.
Communicationwithinthebodyandtheconsequentintegrationofbehaviorwereconsideredtheexclusiveprovinceofthenervoussystemuptothebeginningofthepresentcentury.TheemergenceofendocrinologyasaseparatedisciplinecanprobablybetracedtotheexperimentsofBaylissandStarlingonthehormonesecretion.Thissubstanceissecretedfromcellsintheintestinalwallswhenfoodentersthestomach;ittravelsthroughthebloodstreamandstimulatesthepancreastoliberatepancreaticjuice,whichaidsindigestion.Byshowingthatspecialcellssecretchemicalagentsthatareconveyedbythebloodstreamandregulatedistanttargetorgansortissues.Baylissandstarlingdemonstratedthatchemicalintegrationcouldoccurwithoutparticipationofthenervoussystem.
Theterm“hormone”wasfirstusedwithreferencetosecretion.StarlingderivedthetermfromtheGreekhormone,meaning“toexciteorsetinmotion.Theterm“endocrine”wasintroducedshortlythereafter“Endocrine”isusedtorefertoglandsthatsecretproductsintothebloodstream.Theterm“endocrine”contrastswith“exocrine”,whichisappliedtoglandsthatsecrettheirproductsthoughductstothesiteofaction.Examplesofexocrineglandsarethetearglands,thesweatglands,andthepancreas,whichsecretspancreaticjuicethroughaductintotheintestine.Exocrineglandsarealsocalledductglands,whileendocrineglandsarecalledductless.
1.Whatistheauthor’smainpurposeinthepassage?
A.Toexplainthespecificfunctionsofvarioushormones.
B.Toprovidegeneralinformationabouthormones.
C.Toexplainhowtheterm“hormone”evolved.
D.Toreportonexperimentsinendocrinology.
2.Thepassagesupportswhichofthefollowingconclusions?
A.Thehumanbodyrequireslargeamountsofmosthormones.
B.Synthetichormonescanreplaceaperson’snaturalsupplyofhormonesifnecessary.
C.Thequantityofhormonesproducedandtheireffectsonthebodyarerelatedtoaperson’sage.
D.Theshortchildoftallparentsverylikelyhadahormonedeficiencyearlyinlife.
3.ItcanbeinferredfromthepassagethatbeforetheBaylissandStarlingexperiments,mostpeoplebelievedthatchemicalintegrationoccurredonly___.
A.duringsleep.
B.intheendocrineglands.
C.undercontrolofthenervoussystem.
D.duringstrenuousexercise.
4.Theword“liberate”couldbestbereplacedbywhichofthefollowing?
A.EmancipateB.DischargeC.SurrenderD.Save
5.Accordingtothepassageanothertermforexocrineglandsis___.
A.ductglands
B.endocrineglands
C.ductlessglands
D.intestinalglands.