单项选择题

PassageOne Questions21to25arebasedonthefollowingpassage. Formanyyears，T-shirtsweresimpleshort-sleevedundershirtsformenandboys.T-shirtsusedtobeofonecolor－white.Andsincetheywerewornundershirts，theyweregenerallynotseen. TodaytheT-shirthasbecomefashionable.Itcanbeseeneverywhereandoneveryone.WomenandlittlechildrenwearT-shirtsasdoteenagers，universitystudents，andmenfromallwalksoflife（各行各业）。T-shirtsarewornonplayground，atthebeachorintown.Theycanalsobewornforwork.YetT-shirtsremainrelativelyinexpensiveandlongwearing，aswellaseasytocarefor.Smartbutcomfortableandconvenienttowear，theyhavebecomeoneofAmerican‘snewestideasonfashion. AlthoughT-shirtsarenowavailableinawidevarietyofbrightmaterialsandstyles，themostpopularkindisthetraditionalcottonT-shirtswithasloganorpictureprintedonthefront.AT-shirtmaybearapicture，asingleword，apopular phrase，oranadvertisement.AsT-shirtsarebecomingmoreandmorepopular，newdesignsarecomingupallthetime. WhatisthemostpopularkindofT-shirts？