资源描述：
《2019-2020年高三上学期英语推中试题七选五专练 缺答案》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。
1、2019-2020年高三上学期英语推中试题七选五专练缺答案Secretcodes(密码)keepmessagesprivate.Banks,panies,andgovernmentagenciesusesecretcodesindoingbusiness,especiallywheninformationissentbyputer.Peoplehaveusedsecretcodesforthousandsofyears.36Codebreakingneverlags(落后)farbehindcodemaking.Thescienceof
2、creatingandreadingcodedmessagesiscalledcryptography.Therearethreemaintypesofcryptography.37Forexample,thefirstlettersof“Myelephanteatstoomanyeels”Spelloutthehiddenmessage“Meetme.”38Youmightrepresenteachletterwithanumber,Forexample,Let’snumberthelettersofthealphabet,inord
3、er,from1to26.Ifwesubstituteanumberforeachletter,themessage“Meetme”wouldread“13520135.”Acodeusessymbolstoreplacewords,phrases,orsentences.Toreadthemessageofarealcode,youmusthaveacodebook.39Forexample,”bridge“mightstandfor“meet”and“out”mightstandfor“me.”Themessage“bridgeou
4、t”wouldactuallymean“Meetme.”40However,itisalsohardtokeepacodebooksecretforlong.Socodesmustbechangedfrequently.A.Itisveryhardtobreakacodewithoutthecodebook.B.Inanylanguage,somelettersareusedmorethanothers.C.Onlypeoplewhoknowthekeywordcanreadthemessage.D.Aslongastherehaveb
5、eencodes,peoplehavetriedtobreakthem.E.Youcanhideamessagebyhavingthefirstlettersofeachwordspellitout.F.Withacodebook,youmightwritedownwordsthatwouldstandforotherwords.G.Anotherwaytohideamessageistousesymbolstostandforspecificlettersofthealphabet. B:Everyoneknowsthatfishis
6、goodforhealth. 16 Butitseemsthatmanypeopledon’tcookfishathome.Americanseatonlyaboutfifteenpoundsoffishperpersonperyear,butweeattwiceasmuchfishinrestaurantsasathome.Buying,storing,andcookingfishisn’tdifficult. 17 Thistextisabouthowtobuyandcookfishinaneasyway. 18 Freshfi
7、shshouldsmellsweet:youshouldfeelthatyou’restandingattheocean’sedge.Anyfishyorstrongsmellmeansthefishisn’tfresh. 19 Whenyouhaveboughtafishandarrivehome,you’dbetterstorethefishintherefrigeratorifyoudon’tcookitimmediately,butfreshfishshouldbestoredinyourfridgeforonlyadayor
8、two.Frozenfishisn’tastastyasthefreshone.Therearemanymonmethodsusedtocookfish. 20 First,cleanitandseason
