题目内容：
根据以下材料回答题 Drivingcars,trucksandmotorcyclesisanimportantpartofourlives．Wedoiteverydaytogettowork,toschoolortofriends'houses．
Drivingcanbeveryconvenient,butcanalsocausemanyproblems．Waitinginlineataredlight,adrivermaygetimpatientanddecidejusttodriverightthroughit．Ifanothercariscomingfromtheotherdirection,theremightbeaterribleaccident．Cuttinganothercaroffcanmakeitsdriverangry,sothatdrivercutsoffsomeoneelse．Prettysooneverybodyisangry,andimpatient．
Trafficaccidentsdeclinemillionsofliveseveryyearworldwide．InTaiwanalone,oversevenpeoplearekilledinaccidentseveryday．Theannualdeathrate(年死亡率)fromtrafficaccidentsinTaiwanistwicethatofJapan．
Toallowtraffictomovesmoothlyandsafely,everybodymustfollowtherules．Beforeyoudrive,learnallthetrafficlaws．Thatwayofdrivingissafe,convenientandevenfun!
Theword"convenient"inthepassagemeans__________． A．handy,easytodo
B．thatcanbechanged
C．fondofdrinkingandmerry-making
D．carriagesorothertrucks
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答案解析：