1历年高考试题分项解析之专题七选五1【2016·全国新课标I】根据短文内容,从短文后的选项中选出能填入空白处的最佳选项,选项中有两项为多余选项
Secretcodes(密码)keepmessagesprivate
Banks,companies,andgovernmentagenciesusesecretcodesindoingbusiness,especiallywheninformationissentbycomputer
Peoplehaveusedsecretcodesforthousandsofyears
71Codebreakingneverlags(落后)farbehindcodemaking
Thescienceofcreatingandreadingcodedmessagesiscalledcryptography
Therearethreemaintypesofcryptography
72Forexample,thefirstlettersof“Myelephanteatstoomanyeels”Spelloutthehiddenmessage“Meetme
”73Youmightrepresenteachletterwithanumber,Forexample,Let’snumberthelettersofthealphabet,inorder,from1to26
Ifwesubstituteanumberforeachletter,themessage“Meetme”wouldread“13520135
”Acodeusessymbolstoreplacewords,phrases,orsentences
Toreadthemessageofarealcode,youmusthaveacodebook
74Forexample“bridge“mig