题目内容：
根据以下材料，回答题Therearecollegesthathavefour-yeargraduationratesinthesingledigits.A30%rateisn'tatallunusual,especiallyamongregionalpublicuniversities.
Ifyouareapplyingtocolleges,probablyyourgoalistogetacollegedegree.Someschoolsaremuchmoresuccessfulatgraduatingstudentsthanothers.Ifthemajorityofthestudentsatacollege
don'tgraduateinfouryears,thentheyarespendingmoremoneyforagoalthatwillevadethem.
Whenyouarecalculatingthecostofacollegedegree,youshouldtakegraduateratesintoac-count.Ifmoststudentstakefiveorsixyearstograduate,youshouldn'tplanonincreasedearningpotentialbecauseofyourdegree.
Makesureyouputgraduationratesintocontext.Thereareoftengoodreasonswhysomeschoolshavelargergraduationratesthanothers.
Professionalprogressinfieldssuchasengineering,nursingandeducationaremorelikelytotakefiveyearsthanmanyotherfieldsinthehumanities,scienceandsocialscience.
Manystateuniversitieshavealargepercentageofcommutingstudents,workingstudentsandstudentswithfamilies.Thedemandsonthesestudentsoftenmakinggraduatinginfouryearsdifficult.
Theseschoolsprovideanimportantrolebymakingcollegeaccessibletoall,atthesametime,theywilloftenadmitstudentswhoareentirelyunpreparedforthedemandsofcollegeacademics.
Whatcanweknowfromthefirstparagraph? A．Four-yeargraduationrateisnotlowerthan30percent
B．Bothgettingintocollegesandgraduatingfromthemareeasy
C．ItisveryhardtogetadiplomainsomepublicuniversitiesinAmerica
D．Itiscommonthat70%arenotwillingtogotouniversities
参考答案：
答案解析：