用户群体大的电子商务模式是（）

Ifyoudonotfindtherequiredinformationusingthetipsfromtheprevioussection,thenyouneedtoconsultanonlineservicetofindthepieceofinformationyouwerelookingfor.Threedifferenttypesofserviceshavebeenestablishedovertheyears:crawlers,directoriesandmetasearchengines.Thefirstcrawlerwascreatedbackin1993.ItwascalledtheWorldWideWorm.Itcrawledfromonesitetothenextandindexedallpagesbysavingthecontentofthewebpagesintoahugedatabase.Crawlersorspidersvisitawebpage,readit,andthenfollowlinkstootherpageswithinthesiteandevenfollowlinkstoothersites.Webcrawlersreturntoeachsiteonaregularbasis,suchaseverymonthortwo,tolookforchanges.Everythingacrawlerfindsgoesintoadatabase,whichpeopleareabletoquery.TheadvantageofthewebcrawlersisthattheyhaveanextensivedatabasewithalmostthecompleteInternetindexedinit.Thedisadvantageisthatyougetthousandsofwebpagesasaresponseforalmostanyrequest.Webdirectoriesworkalittledifferently.Firstofalltheycontainastructuredtreeofinformation.Allinformationenteredintothistreeiseitherenteredbythewebmasterwhowantstoannouncehisnewwebpageorbythedirectorymaintainerwholooksatthewebpagessubmitted.ThedirectorieswherewebmasterscansubmitboththeURL(UniformResourceLocator)andthedescriptionnormallycontainmoremisleadinginformation.Gettingintomostwebdirectoriesisacombinationofluckandquality.Althoughanyoneisabletosubmitawebpage,thereisnoguaranteethatacertainpagewillbeincluded.Somedirectorieschargeforsubmission,whichisbasicallyarip-off.Somecrawlersmaintainanassociateddirectory.Ifyoursiteisinthedirectory,therankingofyourwebsitenormallywillbehigher,asitisalreadypre-classified.Manydirectoriesworkwithcrawlerstogether,inordertodeliverresults,whennothingcanbefoundinthedirectory.MetasearchenginesdonothaveadatabasewithURLsanddescriptions.Insteadtheyhaveadatabaseofsearchengines.Ifyouenteryourkeywordsintoametasearchengineitwillsendoutrequeststoallthedirectoriesandcrawlersithasstoredinitsdatabase.ThemetasearchengineswithamoresophisticatedapplicationinthebackgroundareabletodetectdoubleURLswhichcomebackfromthevarioussearchenginesandpresentonlyasingleURLtothecustomer.

34.Crawlerisakindof__________.

A.wormB.searchengineC.serviceD.directory

35.ThedisadvantageofCrawleristhatit__________.

A.providesacompletedatabase

B.takestoomuchtimetofindtheneededinformation

C.providestoomuchuselessinformation

D.givesresponsetoeveryquest

36.Whocaninputinformationtothewebdirectories?

A.Onlywebmasters.

B.Bothdirectorymaintainersandwebmasters.

C.Anyonewhowantstoannounceawebpage.

D.Anyonewhohasfoundanewwebpage.

口令;密码n.p_______________

Relaxationtherapy(=treatment).Ifyoureadthesentenceoutloud,yourbloodpressurewillgoup.Ifyoutalktoanotherperson,itwillgostillhigher.Ifthetalkiswithyourboss,yourpressurewillgoevenhigher.Ifyouspeaktosomeoneoftheoppositesex,yourpressuremayshowlesschangeifyou’remarriedthanifyou’resingle.Dozensoftimeseachday,yourbloodpressurechangeswithwhatyou’refeelinganddoing.These“upsanddowns”takeplaceineveryone,buttheyaremoresevereinpeoplewithhighbloodpressure.Thatdiscoveryisthebasisforthenewesttherapy:controllingbloodpressurebylearningskillstocontroleverydaystress.Manypatientscontroltheirbloodpressurewiththerelaxationresponse.Thistakesfoursimplethings:aquietenvironment,acomfortableposition(sittingorlyingdown),therepeatingofaword,prayerorphraseeachtimeyoubreatheandhavingnoneofotherthoughts.Somethingremarkablehappenswhenyoudothis,accordingtoresearchinBoston.Relaxationofthemindandbodyhastheeffectthatsomeblood-pressurepillswouldhave.What’smore,thebloodpressurestayslower,justasitwouldwithapill,afteryouhavestoppedtherelaxationandhavereturnedtothestressofdailylife.

31.Thefirstparagraphtellsusthereasonwhyyourbloodpressuregoesupisthat__________.

A.youreadaloudasentence

B.themanyoutalktoisyourboss

C.you’renotmarried

D.you’renervous

32.Whichofthefollowingstatementsisnottrue?

A.One’sbloodpressurechangesmanytimeseveryday.

B.Yourbloodpressurechangeswithyourfeelings.

C.Whenyou’redoingdifferentthings,yourbloodpressure,perhaps,isdifferent.

D.Thechangesofbloodpressureonlyhappentopeoplewithhighbloodpressure.

33.Thelastparagraphtellsusrelaxationtherapy__________.

A.needsanewkindofmedicine

B.hasthesameeffectasblood-pressurepills

C.ismorethanblood-pressurepills

D.isworkingandcanbeimproved

名词解释：网络协议