高考英語3500詞配套練習【21-26課時】含答案及解析

高考英語3500詞配套練習【21-26課時】高考英語3500詞配套練習第21課時（see—small）1.單詞拼寫(1)Canyous(縫,縫補)apatchonmyjeans?(2)Thelakeisnotverydeep;it’ss.(3)Putthebookbackontheswhenyou’vefinishedreadingit.(4)Sheswamandsunbathed,wents(觀光)andrelaxed.(5)S(鯊魚)werecirclingaroundourboat.(6)WhydoesthephonealwaysringwhenI’minthes(浴室)?(7)S(奴隸制)wasabolishedintheUSAinthe19thcentury.(8)Useasoftclothtopolishthe(銀)necklace.(9)Jerryiswearingaprettydresswithlongs(袖子).(10)Dad,canwegos(滑冰)thisweekend?2.詞形轉換(1)Sheis(self)andcaresonlyaboutherself.(2)Theworstpartofthedivorcewasthe(separate)fromhisthreechildren.(3)Manyoftheearliest(settle)herediedfromdiseaseandhunger.(4)Sheboughtherhusbandanelectric(shave)ashisbirthdaypresent.(5)Christmasisthebusiest(shop)seasoninWesterncountries.(6)Nothingdisturbedthe(silent)ofthenight.(7)Theytriedto(simple)theprocedureandmakeiteasy.(8)Afterafewyears,hebecamevery(skill)atdrawing.(9)Thewarmthfromthefiremadeherfeel(sleep).(10)Theinsurancepolicyisagainstlong-term(sick)andinjury.3.單項選擇(1)Tooursurprise,thedinnerbillcameto______pounds. A.severalhundred B.severalhundreds C.aseveralhundred (2)______,thehouseneedssomeworkdoneonit. A.Youcansee B.Asyousee C.Asyoucanseeit (3)Hisnewnovel______;veryfewpeoplewouldliketoreadit. A.sellswell B.iswellsold C.sellsbadly D.isbadlysold(4)Whydidshedoathinglikethat?Itdoesn’tseemto______. A.setout B.sellout C.makesense D.settledown(5)Asaprettygirl,Laurais______aboutherweight. A.sensible B.similar C.reasonable D.sensitive(6)Accordingtothecontract,allpayments______bemadeincash. A.ought B.shall C.might D.need(7)Theaccidenthappened______beforemidday. A.short B.slight C.shortly D.slightly(8)TryphoningRobert—he______behomebynow. A.shan’t B.will C.can’t D.should(9)WecametotheUKin1974and______hereeversince. A.lived B.areliving C.havelived D.hadbeenliving(10)Shetappedthedriveron______shoulderandsignaledhimtostopthecar. A.the B.a C.his D./4.選詞填空（必要時改變詞形）settledown outofshape insight sendout setupbesickof takesides situp serveas shutdown(1)Thereweren’tenoughbedsforguests;thesofahadtoabed.(2)I’malwaysforgettingtomycomputerbeforeIgohome.(3)Iwantedtosmoke,buttherewerenoashtrays(煙灰缸).(4)Informationwastointerestedstudents.(5)Anewschoolhasbeeninwhatwasawastelandinthepast.(6)Theoldcouplewouldliketoseetheirdaughter,getmarried,andhavekids.(7)Todaytheathletedidn’tperformwell;hewasfeelingtotally.(8)YouarealwayslateandIyourexcuses.(9)Idon’tmindyoutwoarguing,butdon’taskmeto.(10)Sometimeswejustandwatchvideoallnight.5.句子翻譯(1)他們去機場為兒子送行了。（see）(2)我好像把鑰匙弄丟了。（seem）(3)英吉利海峽把英國和法國分隔開來。（separate）(4)這只是一個玩笑，別當真。（seriously）(5)你昨天沒有來參加晚會，真遺憾。（shame）(6)我們有共同的興趣和愛好。（share）(7)他突然轉變態(tài)度令我們感到吃驚。（shock）(8)學校圖書館眼下缺錢。（short）(9)湯姆的嗓音和布什的很相似。（similar）(10)一看到蛇，她就尖叫起來。（sight）高考英語3500詞配套練習第22課時（smart—store）1.單詞拼寫(1)Thes(聰明)kidgotgoodgradesandwentofftocollege.(2)Tommy,goandwashyourhandswiths.(3)Youneedaspecials(軟件)toviewtheinformationinthefile.(4)Thekinglivesinas(輝煌)palace.(5)Thecriminalwasadangertos(社會).(6)—Howdoyousyourname?—SMITH.(7)Theboydreamedoftravelingtothemooninas(宇宙飛船).(8)Theshoppingmalloccupiesanareaof500smetres.(9)InEnglanddoctorshavetraditionallyenjoyedhighsocials.(10)Ananthastwos.Oneholdsthefoodforitselfandtheotherisforfoodtobesharedwithotherants.2.詞形轉換(1)It’lltakeaboutthreehoursifeverythinggoes(smooth).(2)Tomysurprise,hecametoseemeonone(snow)Januaryday.(3)(4)Dr.SmithworksattheWhiteHouseasa(special)inAfricanpolitics.(5)Theprofessortoldmetocheckmyessaytocorrect(spell)mistakes.(6)HeruncleworksasaWhiteHouse(spoke).(7)About30millionpeopledieof(starve)eachyear.(8)Thievescansell(steal)carsforalotofmoney.(9)Aftertheconference,thepresidentmadea(state)andansweredquestions.(10)Myfatherisaheavy(smoke)—hesmokesalot.3.單項選擇(1)—_______canyoufinishthereport?—Inabouttwodays. A.Howlong B.Howsoon C.Howfar D.Howoften(2)Thelittlethiefranoffsofast_______. A.asnottobecaught B.astonotbecaught C.notastobecaught D.astobenotcaught(3)_______guycalledforyouwhileyouweregone. A.Several B.Any C.Some D.Someone(4)Thebathingproductisnaturaland_______. A.smellswell B.smellsgood C.issmeltwell D.issmeltgood(5)Weputanadvertisementinthelocalpapertolookfora_______secretary. A.spokenGerman B.speakingGerman C.Germanspoken D.German-speaking(6)Ican’tstand_______aroundmewhenI’meating. A.peoplesmoke B.peopletosmoke C.peoplesmoking D.peoplearesmoking(7)_______modernstandards,thecomputerisveryslow. A.By B.With C.On D.In(8)Jack,_______whileItieyourshoes. A.keepsstill B.keepstill C.keepingquiet D.keepquiet(9)—What’swrong?—I’vegotsomething_______inmythroat. A.beingstuck B.tobestuck C.bestuck D.stuck(10)Whoknowwhatwillbe_______forhumanbeingsonmillionyearsfromnow? A.instore B.onstage C.onthespot D.inspirit4.選詞填空（必要時改變詞形）spare speed solid sort state stand spot speak space somehow(1)theymanagedtoclimbinthroughthebathroomwindow.(2)Althoughhedoesn’tawordofFrench,EriclovesFranceverymuch.(3)Thebigpianotakesupmuch.Let’sputitagainstthewall.(4)Thehousewasinaterriblewhenwemovedinbutwecleaneditup.(5)Theblackschoolswerecrowded,whilehundredsofclassroomsemptyinwhiteschools.(6)Thesnackbarsellsburgers,pizzas,thatofthing.(7)(8)Couldyoupossiblymeafewminutes?Iwanttohaveatalkwithyou.(9)Nancy,ifyoudon’tupwewon’tbethereuntilmidnight.(10)Thelakewasfrozen.5.句子翻譯(1)總統(tǒng)立即采取措施，阻止斗爭。（step）(2)你聽起來好像感冒了。（sound）(3)醫(yī)生建議我們定期鍛煉，保持健康。（stay）(4)盯著外賓看是不禮貌的。（stare）(5)卡車正以每小時50英里的速度行駛。（speed）(6)她把空閑的時間全部用來畫畫了。（spend）(7)這種疾病在人群中迅速傳播。（spread）(8)我們學校有120名員工。（staff）(9)我國兒童7歲開始上學。（start）(10)堵車了，所以我遲到了。（stuck）高考英語3500詞配套練習第23課時（storm—television）1.單詞拼寫(1)—Where’sthestation?—Sorry,I’masheremyself.(2)Beforechoosingacareeryoushouldknowyourpersonalsandweaknesses.(3)TheTVsexeducationalprogramisaimedatt,notadults.(4)Moderntmakesitpossibleforpeopletolivelongerthanbefore.(5)Deadleavesfloatedonthesofthewater.(6)Mypossessionswereas(衣箱)fullofclothesandbooks.(7)Abriefs(概要)isgivenonaseparatesheet.(8)Tomisaregularcustomerinthes(超市).(9)Ifyoudrinksomewater,itwillmakethepillseasiertos(吞咽).(10)Thesesausagesarereallyt(可口的).Wheredidyoubuythem?2.介詞填空(1)All______asudden,thelightswentout.(2)Yourcomputerisfarsuperior______mine.(3)Nooneknows______surewhatreallyhappened.(4)Ihaveabsolutelynosympathy______studentswhogetcaughtcheatinginexams.(5)Wereyousuccessful______persuadinghimtochangehismind?(6)Millionsofpeoplearestruggling______survival.(7)Janet’sbeen______alotofstresssincehermotherfellill.(8)Tomlookedup______surpriseasDalewalkedin.(9)Thepalaceissurrounded______ahighwall.(10)Whydon’tyoucomeover______supperonFriday?3.單項選擇(1)—Howaboutsixo’clockoutsidethepark?—That______mefine. A.suits B.meets C.satisfies D.fits(2)The______ofthisexperimentwereallmenaged18-35,andtheywereaskedtowritedownhowtheyfeltduringthetest. A.students B.subjects C.surgeons D.strangers(3)Suddenlyanidea______meandIfounditwouldbeaperfectsolutiontoourproblem. A.submitted B.struck C.sucked D.subscribed(4)Theysuggest______toalawyerbeforeIdoanything. A.metalk B.metotalk C.mytalking D.Iwilltalk(5)—Yousaidyou’dhavefinishedbytoday.—Isaid______! A.notasuchthing B.suchanotthing C.suchnothing D.nosuchthing(6)Thehealthexpert______theimportanceofabalanceddiet. A.stressed B.strengthened C.struggled D.supported(7)Themeeting______takeplaceonTuesday,butwe’vehadtodelayit. A.wassubjectto B.wassupposedto C.wassureto D.wassuitedto(8)Peterwassuspected______governmentsecretstotheenemy. A.togiveoff B.ofgivingoff C.togiveaway D.ofgivingaway(9)Asweallknow,thedoveisa______ofpeace. A.symbol B.system C.sign D.symptom(10)Roger______paintingforawhile,butsoonlostinterest. A.tookon B.tookin C.tookup D.tookover4.選詞填空（必要時改變詞形）sweep swear success straight targetswing swell tease task strengthen(1)Theexperimentwasabig;theprofessorgotwhathewanted.(2)Theroadwasdeadandithadnobendsatall.(3)Ourfriendshiphassteadilyovertheyears.(4)Ididn’tmeantomakeyoumad;Iwasonly.(5)Annhadtheofpreparingtheagendaformeetings.(6)(7)Letyourarmsasyouwalk.(8)Putsomeiceonyourinjuredkneebeforeitup.(9)Thunderstormsthecountryandcausedahugeloss.(10)Dadnottosmokeagain,butmumdidn’tbelievehispromise.5.句子翻譯(1)在學習方面，爸爸對我要求很嚴格。（strict）(2)他們成功地找到了治療頭痛的方法。（succeed）(3)爸爸的背不好。（suffer）(4)這場演出不適合兒童觀看。（suitable）(5)她轉行進入新聞業(yè)之前是一名圖書管理員。（switch）(6)Ben向警察提供了那些涉案人員的姓名。（supply）(7)我們大力支持你的計劃。（support）(8)這孩子在音樂方面有天賦。（talent）(9)她把信撕成碎片，扔到垃圾箱里。（tear）(10)他們談話的聲音很低，我聽不到他們說什么。（talk）高考英語3500詞配套練習第24課時（tell—treat）1.單詞拼寫(1)Waterboilsatatof100degreescentigrade.(2)Thestormbroughtstrongwinds,tandlightning.(3)Tisthedriedbrownleavesthataresmokedincigarettes.(4)Everyyearwelookforburiedtandwehopetofindvaluablethingssuchasgold,silverandjewels.(5)GerrywasborninChinaandhismothertisChinese.(6)ShedoessomeTVwork,butt(戲劇)remainsherfirstlove.(7)Theteachergaveoutcopiesofthenewt(時間表)inthefirstclass.(8)(9)There’sahugequeueintheladies’t(廁所).(10)Alotofoldt(傳統(tǒng))aredyingout.2.詞形轉換(1)Exerciseistheidealwaytoreduce_________(tense)afterahardday.(2)I’llbe_________(thank)foragoodnight’ssleepafterthebusyweekI’vehad.(3)Manyoldpeoplearelivingby_________(them)andtheyfelllonely.(4)Hewrotea_________(thrill),whichtoldanexcitingstoryaboutmurderorcrime.(5)I’vehadsucha_________(tire)day.Ijustwanttotakeabathandgotobed.(6)Heworksasa_________(translate)forthegovernment.(7)Itis_________(tradition)nottoeatmeatonGoodFriday.(8)Weallhadtogoonaspecial_________(train)coursetolearnnewsalestechniques.(9)Asaseasoned(有經驗的)_________(travel),Iknowthevalueofbeingabletospeakatleastafewwordsofalocallanguage.(10)Hewas_________(terrify)atthethoughtofbeingtrappedinthewoods.3.單項選擇(1)Onlytimewill______ifthisagreementwillbringalastingpeace. A.speak B.tell C.say D.talk(2)Thephonewasringing,butbythetimeshe______indoors,it______. A.got;stopped B.hadgot;stopped C.got;hadstopped D.hadgot;hadstopped(3)“Ihavetogo,”shesaid,andwith______shehungupthephone. A.it B.which C.that D.whom(4)Heboughtthetickets______afriendatthestadium. A.through B.thorough C.though D.throughout(5)Recyclingsavesenergy,______acidrain,globalwarmingandairpollution. A.soreduces B.soreducing C.thusreduces D.thusreducing(6)—______isittoday?—It’sTuesday. A.When B.Whattime C.Whatdate D.Whatday(7)Jack,togetherwithhisfriends,______toclimboutofthecanyon. A.decide B.hasdecided C.aretodecide D.aredeciding(8)______existsmusiceverywhereinourlife!Shallwesingtogether? A.There B.Where C.Wherever D.Therefore(9)Theroom,______,ispleasantandairy.Iloveitverymuch. A.beingsmall B.itissmall C.butsmall D.thoughsmall(10) A.believeitornot B.totellthetruth C.that’stosay D.generallyspeaking4.選詞填空（必要時改變詞形）forthemselves clearhisthroat eventhough ontopof intotalintermsof intheory asthough thereyouare touristattraction(1)Theprofessortogetourattentionbeforebeginninghislecture.(2)Itisalsogoodtothinkwhatbadthingscouldhappen.(3),morecompetitionmeanslowerpricesforconsumers.(4).I’vebeenlookingforyou.(5)Pascalwentaheadwiththeexperimentheknewitwasdangerous.(6)HestaredatmeIwereacompletestranger.(7)Therewereprobablyabout40peoplepresentatthemeeting.(8)TheStatueofLibertyisamajor.(9)everythingelse,Inowhavetogotoworkfirst.(10)Parentshavetoteachtheirchildrentothink.5.句子翻譯(1)護士給這個病人量了體溫。（temperature）(2)他回想起他們首次相遇的那一天。（think）(3)我一進房間電話就響了。（than）(4)你能看出這兩種酒的不同嗎？（tell）(5)請把這首詩由中文譯成法語。（translate）(6)這個商店周五營業(yè)到晚上九點鐘。（till）(7)讓我們?yōu)閻鄣氯A的出色工作干杯。（toast）(8)我厭倦了看電視，我們還是出去散散步吧。（tire）(9)我們遇上塞車，被堵住了。（trap）(10)她深深地被這部小說打動了。（touch）高考英語3500詞配套練習第25課時（treatment—visitor）1.單詞拼寫(1)Theislandisshapedlikeat___________(三角形).(2)Hist___________(褲子)wereslightlyshort.(3)Itstartedtorain,soTriciastoppedtoputupheru___________.(4)Theyhiredaprivatet___________tohelptheirsonwithhisEnglish.(5)Hiselderbrotherworksasat___________(卡車)driver.(6)HestudiedphysicsatOxfordU___________.(7)Theirmostv___________(貴重的)belongingswerelockedinasafeinthebedroom.(8)Theshopsellsfreshfruitandv___________.(9)Their2-1v___________(勝利)overtheAustralianswascompletelyunexpected.(10)Thetravelersfoundthev___________(村民)inthevalleywereveryfriendly.2.詞形轉換(1)Thebest____________(treat)foracoldistorestanddrinklotsofwater.(2)Tomisa____________(trouble)childandoftencausesproblems.(3)We’llneverknowthe____________(true)behindtheaccident.(4)Hedoesn’tspeakmuchJapanesebuthecanmakehimself____________(understand).(5)Iwouldhavebeenhereanhourago,but____________(fortunate)Imissedthetrain.(6)It’snot____________(usual)tofeelnervousbeforeanexam.(7)Thejacketisavailablein____________(variety)colors.(8)Thereistoomuchsexand____________(violent)onTVthesedays.(9)TimesSquareattractsmorethan30million____________(visit)annually.(10)Weboughta____________(use)carbecausewecouldn’taffordanewone.3.單項選擇(1)Somethingiswrongwithmycomputer.I’vebeenhavingtrouble________mye-mails. A.check B.tocheck C.checking D.checked(2)After21years,Carl’sdreamofowningahomeofhisownfinally________. A.cametrue B.tocometrue C.cametruly D.comingtruly(3)—Myplantisdying.—Haveyoutried________itinasunnierroom? A.put B.putting C.toput D.tohaveput(4)Lemonscontain________vitaminCasoranges,aswellasvaluableBvitamins. A.twicetheamountof B.thetwiceamountof C.twicethenumberof D.thetwicenumberof(5)Thepossibilityofemployingmorestaffisstill________discussion. A.up B.with C.at D.under(6)Icanunderstand________tolivealoneandbeindependent. A.shewant B.herwant C.herwanting D.hertowant(7)Ithinkyoushouldcomplain—________,ofcourse,youarehappywiththewaythingsare. A.until B.unless C.however D.therefore(8)Dadandmomarebusier;we’reeatingoutmoreoftenthanwe________. A.useto B.usedto C.wereusedto D.areusedto(9)Theseantiqueswillacquiremore________overtime. A.worth B.worthy C.value D.valuable(10)Wesharetheview________peacecanonlybeachievedthroughdialogue. A.which B.what C.where D.that4.選詞填空（必要時改變詞形）turnoff turnout turnup turndown turnoverpayavisitto inmyview upto trueof invain(1)Youcanpayweeklyormonthly—it’syou.(2)Themusicoftheoperaisdull,andthesameistheacting.(3)Theyofferedherthejob,butsheit.(4)Don’tforgettothelightswhenyouleave.(5)Itwasadifficulttime,buteventuallythingsallright.(6)He’lltheshoptohissonwhenheretires.(7)Ihadthoughtmywatchwaslost;buteventuallyitinacoatpocket.(8)Ifyouhavetime,theCityArtGallery.(9),therearefivecriticalchallengesfacingtoday’ssocialmedia.(10)Johnworkedveryhard,butallhiseffortswere.5.句子翻譯(1)孩子們總是?；ㄕ袘蚺蠋?。（trick）(2)如果我不能按時完成這件事，我就要倒霉了。（trouble）(3)在買鞋之前要先試穿一下。（try）(4)直到他開口說話，我才知道他不是英國人。（until）(5)我試著跟他聯系，卻沒有聯系上。（unable）(6)我不習慣午飯吃那么多。（used）(7)有各種各樣的圖案可供選擇。（variety）(8)要是我沒有記錯的話，他昨天回來上班了。（unless）(9)他不愿意向我們提供更多的細節(jié)。（unwilling）(10)我理解現在你心里有多難受。（upset）高考英語3500詞配套練習第26課時（visual—zoom）1.單詞拼寫(1)Readingisoneofthebestwaysofimprovingyourv.(2)Pompeiiwasdestroyedwhenthev(火山)eruptedin79AD.(3)Thev(航海)fromEnglandtoIndiausedtotakesixmonths.(4)Formoreinformation,visitourw(網站).(5)Adamw(吹口哨)happilyonhiswaytowork.(6)Thegirlslikeplayingv(排球).(7)“I’vemissedyou,”hew(低語)inherear.(8)Therewasw(廣泛的)supportforthewar.(9)Wehaveofficesinover56countriesw(在全世界).(10)Ilovestrawberryy(酸奶);ittastesgood.2.詞形轉換(1)Maryworksasa(wait)inarestaurant.(2)Thechildrenstayedcloselytogetherfor(warm).(3)Eachplanhasitsstrengthsand(weak).(4)Heleftasapoorboyandreturnedasanextremely(wealth)man.(5)Fruitandvegetablesaresoldby(weigh)whileeggsaresoldbythedozen.(6)Onthe(west)sideofthecountry,itcanbereallyhot.(7)Ahundredyearsagoitwas(wide)believedthattherewaslifeonMars.(8)Fivelucky(win)willeachreceiveasignedcopyofthealbum.(9)Wehada(wonder)timeinSpain.(10)Hecameinwitha(worry)expression;weknewsomethingwaswrong.3.單項選擇(1)Parentsshouldhavea_________indecidinghowtheirchildrenareeducated. A.voice B.sound C.accent D.tone(2)Lookatthedirtycarpet;itreallywant_________. A.cleaned B.cleaning C.toclean D.beingcleaned(3)Peterwastednotime_________himself;hewantedtoknowalltheguestspresent. A.introducing B.tointroduce C.introduce D.tobeintroducing(4)Thereareseveraldifferentways_________wecandealwiththisproblem. A.which B.inthat C.ofwhich D./(5)Icouldgetyouajobhereifthat’s_________youwant. A.which B.that C.what D./(6)_________IlikeCarterpersonally,Idon’tthinkwhathe’sdoingisright. A.Because B.Though C.Since D.However(7)—Whereonearthhavetheygone?—IwishI_________. A.knew B.know C.willknow D.toknow(8)—I_________ifIcouldborrowyourcar.—Here’sthekey. A.wondered B.willwonder C.waswondering D.hadwondered(9)Thesunwasshining,_________itwasquitecold. A.for B.yet C.so D.despite(10)I_________toapplyforamaster’sdegreeatyouruniversity.MynameisLiMingandIamgoingtograduateinJuly. A.wrote B.willwrite C.waswriting D.amwriting4.選詞填空（必要時改變詞形）writeback writedown wakeup wearout winoverworkon workwith writeto washaway workout(1)FloodsinBangladeshhave__________hundredsofhomes__________.(2)I’ll__________you__________whenit’stimetoleave.(3)Allthisshoppinghas__________us__________andwefeelextremelytired.(4)We’llbeworkinghardoverthenexttendaysto__________theundecidedvoters.(5)She’sjustretiredafter38years__________children.(6)Hehasspentthelasttwoyears__________abookaboutchildcare.(7)Don’tworry.I’msureeverythingwill__________intheend.(8)Isentthemacardonce,buttheynever__________.(9)Thisistheaddress.Doyouwantto__________it__________?(10)I’mgoingto__________themanageraboutthis.5.句子翻譯(1)對不起，讓你久等了。（wait）(2)我提醒過你，不要一個人走回家。（warn）(3)她今天穿的是校服。（wear）(4)他們熱烈歡迎新來的志愿者。（welcome）(5)這本書非常值得一讀。（worth）(6)這個大廳有18米寬。（wide）(7)我不擔心他，他能照顧好自己。（worry）(8)我們移居到了巴黎，在那里我們生活了6年。（where）(9)不管你愿不愿意，我都要走了。（whether）(10)他戒煙后體重增加了。（weight）參考答案第21課時1.單詞拼寫(1)sew (2)shallow (3)shelf (4)sightseeing (5)Sharks(6)shower (7)Slavery (8)silver (9)sleeves (10)skating2.詞形轉換(1)selfish (2)separation (3)settlers (4)shaver (5)shopping(6)silence (7)simplify (8)skilful/skilled (9)sleepy (10)sickness3.單項選擇(1)－(5)ABCCD(6)－(10)BCDCA4.選詞填空(1)serveas (2)shutdown (3)insight (4)sentout (5)setup(6)settledown (7)outofshape (8)amsickof (9)takesides (10)situp5.句子翻譯(1)They’vegonetotheairporttoseetheirsonoff.(2)Iseemtohavelostthekeys.(3)BritainisseparatedfromFrancebytheEnglishChannel.(4)It’sonlyajoke—don’ttakeitseriously!(5)It’sashamethatyoudidn’tco