taken

问题：

回答下面的题目：
TrafficinUurCities
Tilevolumeoftrafficinmanycitiesintheworldtodaycontinuestoexpand．Thiscausesmanyproblems，includingseriousairpollution，lengthydelays，andthegreaterrisk__________(51)accidents．Clearly，somethingmustbedone，butitisoftendifficulttopersuadepeopleto__________(52)theirhabitsandleavetheircarsathome．
Onepossible__________(53)istomakeitmoreexpensiveforpeopletousetheircarsby__________(54)chargesforparkingand__________(55)tougherfinesforanyonewho__________(56)thelaw．Inaddition，driverscouldberequiredtopayforusingparticularroutesatdifferenttimesoftheday．Thissystem，__________(57)as“roadpricin9”，isalreadybeingintroducedina__________(58)ofcities，usingaspecialelectroniccard__________(59)tothewindscreenofthecar．
Anotherwayof__________(60)withtheproblemistoprovidecheapparkingonthe__________(61)ofthecity，andstrictlycontrolthenumberofvehiclesallowedintothecentre．Driversandtheirpassengersthenuseaspecialbus__________(62)forthefinalstageoftheirjourney,Ofcourse．themostimportant__________(63)istoprovidegoodpublictransport．However，togetpeopleto__________(64)thecomfortoftheircars，publictransportmustbefelttobereliable，convenientandcomfortable，withfares__________(65)atanacceptablelevel．

A.blocked
B.kept
C.given

参考答案：C

参考解析：

固定搭配keepatanacceptablelevel表示“保持在一个可接受的水平”。其它三项均不正确。故选C．