Inaworldwhereitseemswealreadyhavetoomuchtodo，andtoomanythingstothinkabout，itseemsthelastthingweneedissomethingnewthatwehavetolearn.Butusecasesdosolveaproblemwithrequirements:with(请作答此空)declarativeequirementsit'shardtodescriblestepsandsequencesofevents.Usecases，statedsimply，allowdescriptionofsequencesofeventsthat，takentogether，leadtoasystemdoingsomethinguseful.Assimpleasthissounds，thisisimportant.Whenconfrontedonlywithapileofrequiements，it'soften()tomakesenseofwhattheauthorsoftherequirementsreallywantedthesystemtodo.Intheprecedingexample，usecasesreducetheambiguityoftherequirementsbyspecifyingexactlywhenandunderwhatconditionscertainbehavioroccurs;assuch，thesequenceofthebehaviorscanberegardedasarequirement.Usecasesareparticularlywellsuitedtocaptureapproaches.Althoughthismaysoundsimple，thefactisthat()equirementcaptureapproaches，withtheiremphasisondeclarativerequirementsand"shall"statements，completelyfailtocapturethe()ofthesystem'sbehavior.Usecasesareasimpleyetpowerfulwaytoexpressthebehaviorofthesysteminwaythatallstakeholderscaneasilyunderstand.But，likeanything，usecasescomewiththeirownproblems，andasusefulastheyare，theycanbe().theresultissomethingthatisasbad，ifnotworse，thattheoriginalproblem.Thereinit'simportanttoutilizeusecaseseffectivelywithoutcreatingagreaterproblemthantheoneyoustartedwith.
A.plenty B.loose C.extra D.strict正确答案A
