多项选择题
A.Use the Properties.USerPreferences object
B.Use the Properties.Settings.Default.Userprefences object
C.Use the ConfigurationManager.AppSettings object during runtime
D.Create the settings by using Application scope
E.Create the settings by using User scope
单项选择题 You create an isntance of a BackgroundWorker Component named backgroundworker1.You discover that when the application attempts to cancel the background process you get an exception from the following code segment： backgroundworker1.CancelAsync（）； You need to configure the BackgroundWorker component appropriately to prevent to application from exception.What should you do？（）
单项选择题 YouarecreatingaWindowsFormsapplicationbyusingthe.NetFramework3.5.Youplantodesignacompositecontrolfortheapplication.Youneedtoderivethecontrolfromabaseclassthatsupportstemplates.Whatshouldyoudo？（）
单项选择题 YouarecreatingaWindowsFormsApplicationbyusingthe.NETFramework3.5.Usersusetheapplicationtoprocessandapproveinvoices.AlistofrecentlyaccessedinvoicesisstoredintheuserssettingssectionoftheApp.configfile.Youneedtomaintainthelistofinvoicesfromthelastpersistedstate.Whatshouldyoudo？（）