为你找到 1000 条关于 测试题1 的结果
关于Python的数字类型,以下选项中描述错误的是()。A1.0是浮点数,不是整数B复数类型虚部为0时,表示为1+0jC整数类型的数值一定不会出现小数点D浮点数也有十进制、二进制、八进制和十六进制等表示方式
下面代码的输出结果是()。x=10y=3print(divmod(x,y))A1,3B(1,3)C3,1D(3,1)
已知列表x=[1,2,3],那么执行语句x=3之后,变量x的地址不变。A正确B错误
1.下列结论正确的是()(A)可微一定连续(B)偏导数存在则函数必可微(C)连续则偏导数存在(D)两个偏导数存在则函数必连续
已知HAc的pKa=4.75,当溶液的pH=1.25时溶液中的主要型体是()
pH<pKa酸式型体为主pH>pKa碱式型体为主pH=pKa二者浓度一样
某指示剂的KHIn=1.0×10-4,其理论变色范围则为()
​变色范围为pKa±1,pKa=-lgka=4
计算分析浓度为0.10mol∙L-1的Na2HPO4水溶液的pH值()。(已知H3PO4的pKa1~pKa3分别是2.12、7.20、12.36.)
Ka2相当于两性物质中酸组分的Ka Na2HPO4作为酸时的解离常数为Ka3Ka1相当于两性物质中碱组分的共轭酸的Ka Na2HPO4作为碱,其共轭酸NaH2PO4的解离常数为Ka2= pH=-lg[H+]=9.78
1.Application的生命周期比Session的生命周期长()。
二只50mL容量瓶,分别为(1)、(2),在(1)号容量瓶中加入Cd2+未知液5.0mL,测得扩散电流为10μA,在(2)号容量瓶中加入Cd2+未知液5.0mL,再0.005mol/LCd2+标准溶液5.0mL,测得扩散电流为15μA,未知溶液中Cd2+的浓度是多少(mol/L)()
注意题目中的容量瓶,意思是将溶液要稀释至50mL然后再开始测定
用钙离子选择性电极直接测定中的血清钙,若Mg2+的浓度为1.300×10-6mol·L-1,Ca2+的浓度为4.00×10-6mol·L-1,钙电极对镁的选择性系数是0.014,则由于镁离子的干扰产生的相对误差为()
钙离子为待测离子,镁离子为干扰离子,0.46%
当相对保留值为1的时候说明两组分的分离很好()
等于1的话,说明二者的保留时间相同,峰重叠
ReadingComprehension(90minutes)Directions:Thereare4passagesinthissection.Eachpassageisfollowedbysomequestionsorunfinishedstatements.ForeachofthemtherearefourchoicesmarkedA),B),C)andD).YoushoulddecideonthebestchoiceandmarkthecorrespondingletteronAnswerSheet.PassageOneQuestions1to5arebasedonthefollowingpassage.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.1.WhatdoweknowaboutLegionnaire'sdiseasefromthepassage?
1.Gettingaroundacityisonething—andthenthere’sthematterofgettingfromonecitytoanother.
ReadingComprehension(90minutes)Directions:Thereare4passagesinthissection.Eachpassageisfollowedbysomequestionsorunfinishedstatements.ForeachofthemtherearefourchoicesmarkedA),B),C)andD).YoushoulddecideonthebestchoiceandmarkthecorrespondingletteronAnswerSheet.PassageOneQuestions1to5arebasedonthefollowingpassage.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.1.WhatdoweknowaboutLegionnaire'sdiseasefromthepassage?
ReadingComprehension(90minutes)Directions:Thereare4passagesinthissection.Eachpassageisfollowedbysomequestionsorunfinishedstatements.ForeachofthemtherearefourchoicesmarkedA),B),C)andD).YoushoulddecideonthebestchoiceandmarkthecorrespondingletteronAnswerSheet.PassageOneQuestions1to5arebasedonthefollowingpassage.Although many of us may feel air-conditioners bring relief from hot, humid or polluted outside air, they pose manypotential health hazards. Much research has looked at how the movement of air inside a closed environment---such as anoffice building---can spread disease or expose people in the building to harmful chemicals.One of the more widely publicized dangers is that of Legionnaire’s disease, which was first recognizedinthe 1970s. This was found to have affected people in buildings with air-conditioning systems in which warmair pumped out of the system’ cooling towers was somehow sucked back into the air intake (通风口),in mostcases due to poor design. The warm air, filled with bacteria,was combined with cooled, conditioned air andwas then circulated around various parts of the building. Studies showed that even people outside such buildings were at risk if they walked past air exhaust pipes.Large air-conditioning systems add water to the air they circulate by means of humidifiers(湿度调节器).Inolder systems, the water used for this process is kept in special reservoirs, the bottoms of which providebreedinggrounds for bacteria which can find their way into the ventilation (通风)system. The risk to human health from this situation has been highlighted by the fact that the immunesystems (免疫系统)of approximately half of workers in air-conditioned office buildings have developed the ability to fight off the organisms found at the bottom of system reservoirs. But chemicals called “biocides”are added to reservoirs to make them germ-free, and they are dangerous in their own right in sufficient quantities, as they often contain compounds strongly linked tocancers.Finally, it should be pointed out that the artificial climatic environment created by air-conditioners canalso affect us. In a natural environment, whether indoor or outdoor, there are small variations in temperature and humidity. Indeed, the human body has long been accustomed to these normal changes. In an air-conditioned living or workingenvironment, however, body temperatures remain well under37℃, our normal temperature. This leads to a weakened immune system and thus greater exposure to diseases such as colds and flu.1.What do we know about Legionnaire's disease from the passage?