题目内容：
根据以下材料回答题 Comparisonsweredrawnbetweenthedevelopmentoftelevisioninthe20thcenturyandthediffu-sionofprintinginthe15thand16thcenturies．Yetmuchhashappened21Aswasdiscussedbe-fore,itwasnot22the19thcenturythatthenewspaperbecamethedominantpre-electronic23,followinginthewakeofthepamphletandthebookandinthe24oftheperiodical．Itwasdur-ingthesametimethatthecommunicationsrevolution25up,beginningwithtransport,therailwaysandleading26throughthetelegraph,thetelephone,radioandmotionpictures27the20thcenturyworldofthemotorcarandtheairplane．Noteveryoneseesthatprocessin28Itisimportanttodoso．
Itisgenerallyrecognized,29,thattheintroductionofthecomputerintheearly20thcen-tury,30bytheinventionoftheintegratedcircuitduringthe1960s,radicallychangedtheprocess,31itsimpactonthemediawasnotimmediately32．Astimewentby,comput-ersbecamesmallerandmorepowerful,andtheybecamepersonaltoo,aswellas33,withdisplaybecomingsharperandstorage34increasing．Theywerethoughtof,likepeople,35generations,withthedistancebetweengenerationsmuch36．
Itwaswithinthecomputeragethattheterminformationsocietybegantobewidelyusedtodescribethe37withinwhichwenowlive．Thecommunicationsrevolutionhas38bothworkandleisureandhowwethinkandfeelbothaboutplaceandtime,buttherehavebeen39viewsaboutitseconomic,political,socialandculturalimplications．Benefitshavebeenweighed40harmfuloutcomes．Andgeneralizationshaveproveddifficult．
第21题应选 A．between
B．before
C．since
D．later
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答案解析：