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人体吸入的O2有2%转化为活性氧，它加速人体衰老，被称为“夺命杀手”．我国科学家尝试用亚硒酸钠 Na2SeO3清除人体内的活性氧，亚硒酸钠Na2SeO3中Se（硒）元素的化合价是（ ）
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人体吸入的O2有2%转化为活性氧它加速人体衰老被称为夺命杀手我国科学家尝试用Na2SeO3清除人体内
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人体吸人的O2有2％转化为活性氧它加速人体衰老被称为夺命杀手我国科学家尝试用亚硒酸钠Na2SeO3清
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人体吸入的O2有2%转化为活性氧它加速人体衰老被称为夺命杀手.我国科学家尝试用Na2SeO3清除人体
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人体吸入的O2有2%转化为活性氧它加速人体衰老被称为夺命杀手我国科学家尝试用Na2SeO3清除人体内
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人体吸入的O2有2％转化为活性氧它加速人体衰老被称为夺命杀手我国科学家尝试用Na2SeO3清除人体内
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人体吸入的O2有2%转化为活性氧它加速人体衰老被称为夺命杀手.我国科学家尝试用亚硒酸钠Na2SeO3
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﹣2
吸入人体内的氧有2%转化为氧化性极强的活性氧它能加速人体衰老被称为生命杀手服用含硒元素Se的化合物亚
作还原剂
作氧化剂
既作氧化剂又作还原剂
既不作氧化剂又不作还原剂
人体吸入的O2有2％转化为活性氧它加速人体衰老被称为夺命杀手我国科学家尝试用Na2SeO3清除人体内
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人体吸入的O2有2%的转化为活性氧它能加速人体的衰老被称为夺命杀手.我国科学家尝试用亚硒酸钠Na2S
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吸入人体的氧有2%转化为氧化性极强的活性氧它能加速人体衰老被称为生命杀手服用含硒元素Se的化合物亚硒
作还原剂
作氧化剂
既作氧化剂又作还原剂
既不作氧化剂又不作还原剂
人体吸入的O2有2%转化为活性氧它加速人体衰老被称为夺命杀手我国科学家尝试用Na2SeO3清除人体内
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人体吸人的O2有2％转化为活性氧它加速人体衰老被称为夺命杀手我国科学家尝试用Na2SeO3清除人体内
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人体吸入的氧气有2%转化成活性氧它因加速人体衰老而被称为夺命杀手我国科学家正尝试用Na2SeO3清除
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人体吸入的O2有2％转化为活性氧它加速人体衰老被称为夺命杀手我国科学家尝试用Na2SeO3清除人体内
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吸进人体内的O2有2%转化为氧化性极强的活性氧这些活性氧能加速人体衰老被称为生命杀手中国科学家尝试用
还原剂
氧化剂
既是氧化剂，又是还原剂
以上均不是
人体吸入的O.2中有2％转化为活性氧加速人体衰老被称为夺命杀手科学家尝试用Na2SeO3清除人体内的
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-2
吸入人体内的O2有2%转化为氧化性极强的活性氧它能加速人体的衰老被称为生命杀手服用含硒Se元素的化合
氧化剂
还原剂
既是氧化剂又是还原剂
既不是氧化剂又不是还原剂
人体吸入的O2有2%转化为活性氧它可加速人体衰老被称为夺命杀手我国科学家尝试用Na2SeO3清除人体
＋2
＋4
＋6
－2
人体吸入的O2有2％转化为活性氧它加速人体衰老被称为夺命杀手我国科学家尝试用Na2SeO3清除人体内
+2
+4
+6
-2
吸进人体的氧有2%转化为氧化性极强的活性氧这些活性氧加速人体衰老被称为生命杀手科学家试用Na2SeO
氧化剂
还原剂
既是氧化剂又是还原剂
以上均不是
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10分Whenathletesatthe2020TokyoOlympicscollecttheirmedalsthey'llnotonlybewearingsomethingthatcelebratestheirsportingperformancebutsomethingthatsymbolizeslastingness.Forboththe2020OlympicsandParalympicsorganizersaimtomakeallofthegoldsilverandbronzemedalsoutofusedelectronics.Thisstrongmessageabouthowtomakeuseofe﹣wastehasgottenaofJapaninvolved. StartinginApril2017theJapaneseOlympicCommitteebegancollectingoldlaptopsdigitalcamerassmartphonesandotherabandonedelectronics.Theinitiative倡议hasachievedgreatsuccess.Alreadythequantityneededforbronzemedalshasbeenmetandthey'reinthehomestretchforsilverandgoldmedalsmeaningthecollectionprocesscanpackupattheendofMarch. Whenlookingjustatthenumberofcellphonescollectedtheamountofwasteisshocking.Inaperiodofabout18monthsalittleover5millionsmartphoneswerecollectedthankstocooperationwithNTTDOCOMO.Japan'slargestmobilephoneoperatorallowedthepublictoturninphonesattheirshopswhichcountedalotintheproject'ssuccess. Afterbeingtakenapartandsortedthesmallelectronicsunderwentasmeltingprocesstoextract提炼allthegoldsilverandbronzeelements.Thankstothisinitiativetheworldwidestrugglewith﹣wastewillhaveaglobalplatform.AccordingtoastudypublishedbytheUnitedNationsUniversity﹣44.7millionmetrictonsofe﹣wasteweremadein2016.Only20%ofthatwasactuallyrecycled.Unfortunatelythisfigureissettorisesignificantlyinthecomingyearsmovingto52.2millionmetrictonsby2021.SowhiletheTokyoOlympicsinitiativemightbejustadropinthebucketit5sagoodstartinshowingwhatthepubliccandoifthey'remademoreawareoftheissue. 1WhatcanbelearntaboutTokyoOlympicsinitiativefromthepassage? A.E﹣wasteintheworldisincreasingsignificantly. B.Ifseasytogetelementsneededfromtheusedelectronics. C.Onlyproducersofelectronicsparticipatedintheproject. D.NTTDOCOMOcontributedtothesuccessoftheproject. 2WhichcanbestreplacetheunderlinedwordhomestretchinParagraph2? A.startingperiod B.collectioneffort C.finalstage D.hardsearch 3WhatinfluencedoestheTokyoOlympicsinitiativehave? A.Itoffersaneffectivemethodtosolvetheproblemofe﹣waste. B.Itshowsthepowerofadvancedtechnologyindailylife. C.Itsavestheexpensespentinmakingallthemedals. D.Itencouragesthepublic'sinvolvementindealingwithe﹣waste. 4Whatisthewriter'sattitudetotheTokyoOlympicsinitiative? A.Positive B.Negative C.Ambiguous D.Indifferent
诗云“满架蔷薇一院香”能闻到一院花香的原因是
为防止骨质疏松应补充的元素是
15分假定你是校英文报主编李华.由于英文报规模扩大现急需招聘一名助理编辑.请你以AnEnglishEditorwanted为题用英语写一则招聘启事.内容包括 1.职位描述 2.应聘要求 3.联系方式. 注意1.词数80左右2.可以适当增加细节以使行文连贯.
甲乙两种物质的溶解度曲线如图所示．下列叙述正确的是
阅读下面科普短文原文作者王龙飞等有删改． 纯净的臭氧O3在常温下是天蓝色的气体有难闻的鱼腥臭味不稳定易转化为氧气．它虽然是空气质量播报中提及的大气污染物但臭氧层中的臭氧能吸收紫外线保护地面生物不受伤害．而且近年来臭氧的应用发展较快很受人们的重视． 生产中大量使用的臭氧通常有以下方法制得． 臭氧处理饮用水．早在19世纪中期的欧洲臭氧已被用于饮用水处理．由于臭氧有强氧化性可以与水中的有害化合物如硫化铅发生反应处理效果好不会产生异味． 臭氧做漂白剂．许多有机色素的分子遇臭氧后会被破坏成为无色物质．因此臭氧可作为漂白剂用来漂白麻棉纸张等．实践证明臭氧的漂白作用是氯气的15倍之多． 臭氧用于医用消毒．与传统的消毒剂氯气相比臭氧有许多优点如表1所示． 表1臭氧和氯气的消毒情况对比 依据文章内容回答下列问题． 1臭氧的相对分子质量为． 2臭氧处理饮用水时利用了臭氧的填“物理”或“化学”性质． 3臭氧转化为氧气的微观示意图如图请在方框中补全相应微粒的图示． 4为了快速杀灭病毒应选择的消毒剂是． 5下列关于臭氧的说法中正确的是． A．臭氧的漂白作用比氯气强 B．由氧气制得臭氧的过程中既有物理变化也有化学变化 C．臭氧在生产生活中有很多用途对人类有益无害 D．臭氧稳定性差不利于储存其应用可能会受到限制
根据如图从A或B两题中任选一个作答若两题均作答按A计分．
下列物质放入水中能形成溶液的是
西红柿炖牛肉味道鲜美营养丰富． 1牛肉中富含的营养素是． 2西红柿中含“铁”缺“铁”会引起填字母序号． A．佝偻病B．贫血C．骨质疏松
食用油脂与人体健康食用油脂能供给人体必需脂肪酸促进脂溶性维生素的吸收是最常用的食品和调味品．食用油脂是一种高热量食品每克油脂在体内氧化释放37.7kJ的热量比等质量的糖和蛋白质高一倍多再加上不同油脂成分的差异性使如何选择和使用食用油脂存在不少盲区和误区．食用油脂中99%以上是脂肪酸还含有维生素AE少量矿物元素钙钾等．食用油中脂肪酸种类繁多主要分类方法见图1．不同油脂中各种脂肪酸的含量不同常见食用油中脂肪酸组成%如表．脂肪酸不仅种类繁多功能也各异．饱和脂肪酸能平衡血浆中脂肪酸浓度摄入过高会导致胆固醇甘油三酯等升高继而引发动脉管腔狭窄单不饱和脂肪酸分子内的碳原子之间存在一个碳碳双键C＝C主要是油酸C18H34O2ω﹣9油酸能降低总胆固醇和有害胆固醇但不会降低有益胆固醇多不饱和脂肪酸主要有亚油酸C18H32O2ω﹣6和α﹣亚麻酸C18H30O2ω﹣3它们是人体必需脂肪酸而且人体不能合成必需从食物中摄入．亚油酸有血管清道夫的美誉能防止血清胆固醇在血管壁沉积α﹣亚麻酸在人体分解后形成生命活性因子DHA和EPA是大脑的重要营养要素DHA能提高记忆力和思维能力EPA能降低血液中胆固醇和甘油三酯的含量降低血液粘稠度．天然状态下不饱和脂肪酸多数为顺式脂肪酸．反式脂肪酸主要存在于奶油类煎炸类和烘烤类食品中受加热过程影响油品中反式脂肪酸含量质量分数/%发生变化．其变化过程如图2所示．反式脂肪酸可妨碍必需脂肪酸在人体内的代谢提高总胆固醇与高密度脂蛋白的比例从而增加冠心病发病风险．依据文中内容回答下列问题1食用油脂能为人体提供的营养素有．2按油脂分类花生油属于．3常见食用油中多不饱和脂肪酸含量最高的是．4关于食用油脂下列说法正确的是．A．应少吃油炸烘焙类食品B．食物营养素中热量最高的是脂肪C．烹调食物时最好将油温控制在260℃以下D．油酸和亚油酸分子中碳碳双键的个数不同
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“大理石”是常见的筑装饰材料容易受到酸雨含硫酸的侵蚀原因是用化学方程式表示．
10分Forcollegegraduatesitisofvitalimportancetowriteapplicationletterswell.1Itshouldstateclearlythejobyouwantandshouldtellwhatyouhavedone.Itshouldbesimplehumanpersonalandbriefwithoutleavingoutanynecessaryfacts. Inwritingaletterofapplicationkeepinmindthatthethingsapossibleemployerismostlikelytowanttoknowaboutareyourqualificationsyourachievementsandyouraims.2Ifthefirstfewsentencesfailtowinthereader'sattentiontherestofthelettermaynotbecontinuedatall.Trytokeyyouropeningremarkstotheneedsorinterestsoftheemployernottoyourownneedsordesires.ForexampleinsteadofbeginningwithIsawyouradvertisementintoday'snewspaperyoumightsayIhavemadeacarefulstudyofyouradvertisingduringthepastsixmonthsorIhavemadeasurveyinmyneighborhoodtofindouthowmanyhousewivesuseyourproductandwhytheylikeit. 3Beclearaboutthekindofjobforwhichyouarenowapplying.Collegegraduateslookingfortheirfirstpositionsoftenaskwhattheycanprovideinaletterandwhatifemployerswarnexperiencewhichnaturallynobeginnerhas.4 Itisimportanttowriteagoodstrongclosingforyourletter.Makeaspecificrequestforanintervieworgivethepossibleemployersomethingdefinitetodoorexpect.5Thatmakesiteasierforapossibleemployertogetintouchinyou. A.Hereareafewsuggestionsforyoutoprepareyourselfbetterforyourinterview. B.Anexcellentideaistoencloseastampedself﹣addressedenvelopewithyourletter. C.Theansweristhateverythingyouhaveeverdoneisexperience. D.Don'tbeafraidofbeinganewhand. E.Trytoavoidwritingingeneral. FThepurposeofaletterofapplicationistohelpyoutosellyourself. G.Theopeningparagraphisperhapsthemostimport.
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6分Differentcountrieshavedifferentcustomsespeciallyintablemanners.Somedininghabitsmaybeconsideredcivilizedinonecountrybutrudeinanother.Herearesomeinterestingfactsaboutsomecountries. France WheninFrancesplittingthebillAAwithfellowdinersshouldbeavoidedwhenpossible.You'reexpectedtooffertopaytheentirebillorsomeoneelseisexpectedtodg.so.OfcourseaccordingtoFrenchTodaytherearesomecasesWheresplittingthebillisOKlikewhendiningoutwithalargegroupofpeopleorwithcoworkers. Columbia Ifyou'reusedtocleaningyourplateyoumightwanttoconsidernotdoingsowhendininginColombiaIt'sconsideredrudetoleaveanemptyplatebecauseit'sasifyou'retellingyourhostthatheorshedidn'tgiveyouenoughfood. Australia InAustraliapeopletypicallyprefernottodiscussbusinessmattersoveramealaccordingtoEtiquetteScholarOfcourseitdependsonthepersonorgroupyou'rewithbutyoushouldpayattentiontoanycuesfromyourfellowdiningcompanionsforgoodmeasure. Kazakhstan InAmericait'sprettytypicaltogetannoyedwhenyourbaristadoesn'tfillyourcupalltheup.ButinKazakhstanitactuallyleaveyousatisfiedsinceitisagoodsign.AccordingtoEveryCulturehalf﹣filledcupsaremeanttokeepyourteawarmsinceyourhostwillcontinuouslyfillyourcupasawaytokeeptheinteractiongoingIfyourhostorserverweretofillyourcupwithteahoweveritisasignthattheymightwantyoutoleaveaccordingtoCommisceoGlobal. 1InFrancewithwhomissplittingthebillOKnowwhendining? A.yourchildren B.yoursweethearts C.yourcoworkers D.yourparents 2Inwhichcountryyouhadbetterleavesomefoodontheplate? A.France B.Columbia C.Australia D.Kazakhstan 3InKazakhstanifthehostfillsyourcupwithteaitmeansthat. A.youshouldleave B.youlikethetea C.youarethirsty D.theteatastesgood
15分Scotlandisauniqueplacewithlonghistorywhereyoucanfindnoble1palaceandcastles.Ithassomeof2mostbeautifulcitiesinEuropelivingwitnessofaproudandexcellentpast. 3discoverthetruesoulofScotlandtodaywehavetogotowardsthenorthernregionstotheGrampianMountainsItwasdifficulttofarmbuttheScotsdefeatedtheenvironmentwithstrongarms.Thehistoryofthisancientstruggleanditspeople'sancientloveforthehardlandare4apparentshownintheAngusFolkMuseum.Youcangetafeelofthetypicalruralatmosphereofpasttimesfromthedailyman﹣madeobjects5displayhere. FromcoastalAberdeen6theinsideoftheGrampianMountainsthererunstheCastleTrailaroadwithmanyfortresses要塞7arewitnessesof8continuefightsagainsttheruleofEnglandinScottishhistory. Another9attracthereisalegendarymonstertheLochNessMonster.Isthismonsterwhich10collectagood3000sightingsoverthelast50yearsrealorimaginary?Tomeetthecuriosityaboutitapriceof500000poundshasbeenputonthemonster'shead.
化学小组同学用如图所示装置做了2个兴趣实验． 1若观察到a中固体减少有大量的气泡产生b中溶液无明显变化．推测固体可能是下列物质中的填字母序号． A．银B．锌C．氢氧化钙D．碳酸钙 2若固体为碳酸氢钠粉末则整个装置中可观察到的现象有．
从1世纪起铁便成了一种最主要的金属材料． 1上述三种铁矿石的主要成分属于氧化物的是． 2工业上用一氧化碳和赤铁矿炼铁的原理是用化学方程式表示．
空气的成分中体积分数约占21%的是
下列物质在氧气中燃烧火星四射生成黑色固体的是
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海带中富含碘元素I可利用反应2NaI+Cl2═2NaCl+I2从海带中提取碘单质I2．此反应属于
下列物质中含有氧分子的是
25分2019年元宵节LanternFestival故宫首次开放衣场旅游盛况空前假定你是李华你的朋友Jack参观了元宵故宫灯会lanternshow.现你校文学社LiteratureClub要征集役游故宫灯会经历的稿件请你写一封电子邮件邀请Jack投稿内容包括 1.稿件主题夜游故言灯会经历和感受 2.截止日期2019年3月31日 3.投稿方式邮箱20190678@qq.com 注意1.词数100左右 2.可适当增加细节以使行文连贯. DearJack Yours LiHua
8分Ifyouaskmostpeoplewhatwatertasteslikethey'llprobablytellyouthatwaterhasnotasteandtheymaygiveyouafunnylook.Butifyouwereafruitflyaskinganotherfruitflythatquestionmighthaveadifferentanswer. Toafruitflywaterhasataste.Scientistswanttoknowhowthefruitflyknowswaterbecausethisinformationmayhelpinlearninghowotheranimalsmanagetousewaterintherightway.Waterisveryimportanttolifebuttoomuchortoolittlecanbedeadlytoalivingcreature.Sobyunderstandinghowthefruitflytasteswaterresearchersmaylearnmoreaboutotherlivingthings. AccordingtothenewstudyaproteincalledPPK28makesitpossibleforaflytotastewater.Proteinsbuildcellsandtissuesfightdiseaseandcarrymessagesbetweencells.It'snotsurprisingthataproteinisresponsibleforthefruitfly'sabilitytotastewater. ThePPK28proteinispartofalargerfamilyofsimilarproteins.Oneoftheserelatedproteinsisusedbymammalsincludinghumanstotastesalt.Scientistshavenotfoundaproteinthatenableshumanstotastewater.IntheexperimentCameronandhisteamcomparednormalfruitflieswithfruitflieswhosetastecellshadhadbeendisabled.ThefruitfliesweregivenaspecialchemicalthatwouldglowwhentheflyusedthePPK28protein.Thenthescientistsledthefliestowater.WhenthenormalfliestastedthewaterthePPK28proteinlitup﹣showingthatitwasinuse.Thefruitflyinparticularissointerestingthatsomescientistsarehardatworkcreatingacompletemapofthefruitflybrain.Thismapwillshowallofafly'sneuronsandhelpscientistsunderstandhowtheneuronsworktogether. 1Howdomostpeoplefeelwhenaskedthetasteofwater? A.Disappointed B.Frightened. C.Amused D.Disgusted. 2Whydoscientistswanttounderstandhowthefruitflyknowswater? A.Todecreasethenumberofthefruitfly. B.Toknowmoreaboutothercreatures. C.Tomanagetousewatercorrectly. D.Todescribethetasteofwater. 3WhatdoweknowaboutthePPk28protein? A.Itcanmakehumanstastesalt. B.Itenablesthefruitflytotastewater. C.Thefruitflycan'tlivewithoutit. D.Thefruitflyusesittoavoidillnesses. 4Whatwillthescientistscontinuetoworkat? A.MakingthePPk28protein. B.Tellingmoreinformationaboutcells. C.Creatingmapsofhumanbrains. D.Studyingthefruitfly'sneuronsystems.
铜可用于制造传统的炭火锅下列性质与此用途无关的是
干冰常用于人工降雨利用了干冰的性质．
化学晚会上小明表演了一个小魔术﹣﹣“矿泉水”变成“牛奶”“雪碧”和“红酒”．回答下列问题 1“矿泉水”实际是石灰水加入液体A后出现白色浑浊形似牛奶该过程发生反应的化学方程式为． 2“牛奶”中加入B有大量气泡产生变成雪碧则B物质是该过程发生的化学反应最多有个． 3C是一种紫色的溶液滴入“雪碧”中变为红色则雪碧的组成是．
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