ACanIndoorPlantsReallyPurifytheAir?Plantsareveryimportanttohumanlife.Throughphotosynthesis(光合作用),theytransformcarbondioxideintofreshoxygen.Theyareassumedtoremovetoxinsfromtheairwebreathe—butisthistrue?OnefamousNASAexperiment,publishedin1989,hasfound(1)__________thatindoorplantscancleantheairbyremovingpollutantscausingcancer.Laterresearchhasfound(2)__________thatsoilmicro-organismsinthepottedplantalsoplayapartincleaningindoorair.Basedonthisresearch,somescientistssayhouseplantsareeffectivenaturalairpurifiers,andthebiggerandleafiertheplant,thebetter.Theamountofleafsurfaceareainfluencestherateofairpurification.Others,however,saytheevidence(3)__________thatplantscaneffectivelyaccomplishthisfeat(功績(jī))isfarfromconclusive.“Therearenodefinitivestudiestoshow(4)__________thathavingindoorplantscansignificantlyincreasetheairqualityinyourhome,”accordingtoLuzClaudio,aprofessorofenvironmentalmedicineandpublichealth.“There’snoquestion(5)__________thatplantsarecapableofremovingvolatile(易揮發(fā)的)chemicaltoxinsfromtheairunderlaboratoryconditions,”saysClaudio.Butinyourhomeorofficespace,thenotion(6)__________thatputtingafewplantstogethercanpurifyyourairdoesn’thavemuchhardsciencetobackitup.Mostresearcheffortstodate,includingtheNASAstudy,placedindoorplantsinsmall,(28)sealedenvironmentstoassess(7)____________________howmuchair-purifyingpowertheyhave.“Butthosestudiesaren’treallyapplicableto(8)__________whathappensinahouse.Inmanycases,theairinyourhomecompletelyturnsover—thatis,exchangesplaceswithoutdoorair—onceeveryhour.Inmostinstances,airexchangewiththeoutsidehasagreatereffectonindoorairqualitythanplants.”saysStanleyKays,aprofessorofhorticulture(園藝學(xué)).Disappointedasmanypeoplemaybeby(9)__________whatKayssaid,theprofessoralsomadeitclear(10)__________thathebelieveshouseplantsarebeneficial.Studieshaveshownplantscanknockoutstressandmakepeoplefeelhappier.Moreresearchshowsspendingtimearoundnaturehasapositiveeffectonaperson’smoodandenergylevels.BDentalhealth:BrushwithconfidenceChildrenshouldbetaughttobrushtheirteethregularly.Butthesuspicionremainsamongsomepeople,dentistsincluded,(1)__________thatevenso,certainchildrenaredoomedtodevelopdentalcavities.Thehypothesisbehindthisfearis(2)__________thatsomecombinationsofgenesmaygiverisetothesortsoforalbacteriawhichareresponsibleforcavities.Iftrue,thatwouldbesadfortheyoungstersconcerned.ButastudyjustpublishedinCellHostandMicrobe,byAndresGomezandKarenNelsonoftheJ.CraigVenterInstitute,inSanDiego,suggests(3)__________thatitisn’ttrue.Themouthishometomanyspeciesofmicrobes.Mostaregood.Some,though,arewellknowntosecreteacidicwasteproductswhenfedsugar.Thisacidityweakensteeth,causingthemtodecay.Totrytofindout(4)__________whetherachild’sgenesplayanyroleinencouragingsuchacid-secretingbugs,DrGomezandDrNelsonsetupanexperimentwithtwins.Their“volunteers”were280pairsoffraternaltwinsand205pairsofidenticaltwins,allagedbetweenfiveand11,whohadnottakenantibioticsduringtheprevioussixmonths.Thechildrenwereaskedtostopbrushingtheirteeththeeveningandthemorningbeforethecrucialmomentofdatacollection.Thiswas(5)__________whentheresearchersswabbedthechildren’sgingivalsulci（thecleftsbetweenteethandgums,inwhichbacteriacollect）tofindout(6)__________whatwasthere.Thechildrenalsohadtheirteethscoredbydentistsasbelongingtooneofthreecategories:havingnosignsofcurrentorpreiousdentalcaities:haingsinsofcurrentorpreiouscaitiesafetingtheenael（atootshard,outerlaer）;(7)__________(8)__________(9)__________(10)__________(11)__________(12)__________C“Mondaymorningfeeling”couldbeacrushingpaininthechestwhichleavesyousweatingandgaspingforbreath.RecentresearchfromGermanyandItalyshows(1)__________thatheartattacksaremorecommononMondaymorningsanddoctorsblamethestressofreturningtoworkaftertheweekendbreak.

Theriskofhavingaheartattackonanygivendayshouldbeoneinseven,butasix-yearstudyhelpedbyresearchersattheFreeUniversityofBerlinofmorethan2,600Germansrevealed(2)__________thattheaveragepersonhada20percenthigherchanceofhavingaheartattackonaMondaythanonanyotherday.

WorkingGermansareparticularlynotprotectedagainstattack,witha33percenthigherriskatthebeginningoftheworkingweek.Non-workers,bycomparison,appeartobenomoreatriskonaMondaythananyotherday.

Astudyof11,000Italiansproved8amonaMondaymorningasthemoststressfultimefortheheart,andbothstudiesshowedthatSundayistheleaststressfulday,withfewerheartattacksinbothcountries.

Thefindingscouldleadtoabetterunderstandingof(3)__________whatistheimmediatecauseofheartattacks,accordingtoDr.StefanWillichoftheFreeUniversity.“Weknowalotaboutlong-termriskfactorssuchassmokingandcholesterol（膽固醇）butwedon’tknow(4)__________whatactuallycausesheartattacks,sowecan’tmakespecificrecommendationsabout(5)__________howtopreventthem,”hesaid.

Mondaymorningshaveadoublehelpingofstressfortheworkingbodyasitmakesarapidchangefromsleeptoactivity,andfromtherelaxingweekendtothepressuresofwork.“Whenpeoplegetup,theirbloodpressureandheartrategoupandtherearehormonal（荷爾蒙的）changesintheirbodies,”Willichexplained.“Allthesethingscanhaveanunfavorableeffectinthebloodsystemandincreasetheriskofaclot（血凝塊）inthearteries（動(dòng)脈）whichwillcauseaheartattack.”“Whenpeoplereturntoworkafteraweekendoff,thepaceoftheirlifechanges.Theyhaveahigherworkload,morestress,moreangerandmorephysicalactivity,”saidWillich.“Weneedtoknow(6)__________howtheseeventscausechangesinthebodybeforewecanunderstand(7)__________if/whethertheycauseheartattacks