丙烯和丁烯的混合物进入气相色谱柱后测得：空气、丙烯、丁烯保留时间分别为0.5,3.5,4.8min。丙烯在这个柱上的分配比是（）

射频识别技术属于物联网产业链的（）环节。

已知x1=(2,4)T,x2=(4,8)T是某线性规划问题的两个最优解，则下面也是该线性规划问题最优解的是()

中国电视采用那种制式？

人与自然相处时应承担的重要责任是（）。

判断指令对错SHLAX，4

要使寄存器AL中的高4位不变，低4位为0，所用指令为（）。

Althoughmanyofusmayfeelair-conditionersbringrelieffromhot,humidorpollutedoutsideair,theyposemanypotentialhealthhazards.Muchresearchhaslookedathowthemovementofairinsideaclosedenvironment---suchasanofficebuilding---canspreaddiseaseorexposepeopleinthebuildingtoharmfulchemicals.OneofthemorewidelypublicizeddangersisthatofLegionnaire’sdisease,whichwasfirstrecognizedinthe1970s.Thiswasfoundtohaveaffectedpeopleinbuildingswithair-conditioningsystemsinwhichwarmairpumpedoutofthesystem’coolingtowerswassomehowsuckedbackintotheairintake(通风口),inmostcasesduetopoordesign.Thewarmair,filledwithbacteria,wascombinedwithcooled,conditionedairandwasthencirculatedaroundvariouspartsofthebuilding.Studiesshowedthatevenpeopleoutsidesuchbuildingswereatriskiftheywalkedpastairexhaustpipes.Largeair-conditioningsystemsaddwatertotheairtheycirculatebymeansofhumidifiers(湿度调节器).Inoldersystems,thewaterusedforthisprocessiskeptinspecialreservoirs,thebottomsofwhichprovidebreedinggroundsforbacteriawhichcanfindtheirwayintotheventilation(通风)system.Therisktohumanhealthfromthissituationhasbeenhighlightedbythefactthattheimmunesystems(免疫系统)ofapproximatelyhalfofworkersinair-conditionedofficebuildingshavedevelopedtheabilitytofightofftheorganismsfoundatthebottomofsystemreservoirs.Butchemicalscalled“biocides”areaddedtoreservoirstomakethemgerm-free,andtheyaredangerousintheirownrightinsufficientquantities,astheyoftencontaincompoundsstronglylinkedtocancers.Finally,itshouldbepointedoutthattheartificialclimaticenvironmentcreatedbyair-conditionerscanalsoaffectus.Inanaturalenvironment,whetherindoororoutdoor,therearesmallvariationsintemperatureandhumidity.Indeed,thehumanbodyhaslongbeenaccustomedtothesenormalchanges.Inanair-conditionedlivingorworkingenvironment,however,bodytemperaturesremainwellunder37℃,ournormaltemperature.Thisleadstoaweakenedimmunesystemandthusgreaterexposuretodiseasessuchascoldsandflu.Theauthormostprobablywantsthereaderstotreatbiocideswithanattitudeof_.

49.Whatdowelearnaboutthemedicalcommunity?A)Theynowhaveastronginterestinresearchonaging.B)Theydifferfromtheacademiccirclesintheirviewonaging.C)Theycancontributetopeople’shealthonlytoalimitedextent.D)Theyhavewaystointerveneinpeople'sagingprocess.

4.计划经济与市场经济的主要区别在于（）

4

下列活动中，不可以委托代理的是（）。

论文选题的要求

下列权力中，不属于物权的是

互联网商务的软肋在()。