单项选择题
A.Extend the Control class.
B.Extend the ContainerControl class.
C.Create protected accesses for each control property.
D.Create public accesses for the properties of the BindingSource control.
单项选择题 YouarecreatingaWindowsFormsapplicationbyusingthe.NetFramework3.5Youplantodisplaydetailedhelpinstructionsforeachcontrolintheform.Youcreateahelpfile.YouconfigureaHelpProvidercomponentontheform.YouneedtodisplaythehelpfileforthecontrolthatisfocusedwhentheF1keyispressed.WhichmethodoftheHelpProviderclassshouldyoucallforeachcontrol？（）
多项选择题 YouaredevelopingaWindowsFormsApplicationbyusingthe.NETFramework3.5.YouplantocreateacustomizedPrintPreviewdialogboxintheapplication.Youneedtoensurethatuserscanpreviewtheirdocumentsbeforeprinting.Whichtwoactionsshouldyouperform？（）
单项选择题 YouaredevelopingaWindowsFormsApplicationbyusingthe.NETFramework3.5.Youplantodesignacompositecustomcontrolfortheapplication.YouincludeaListBoxcontrolhasapropertythatprovidestheitemcountoftheListBoxcontrol.Youneedtoensurethatthepropertycannotbeaccessedatdesigntime.Whichattributeshouldyouuse？（）