You are creating a Windows Forms application by using the .NET Framework 3.5. You create a new form in the application.You add a ContextMenuStrip control named dctxMenu to the form. You have a user defined class named CustomControl.You write the following code segment in the application （Line numbers are included for reference only ）
CustomControl myControl = new CustomControl（）； 
You need to ensure that an instance of CustomControl is displayed on the form as a toplevel item of the ctxMenu control.  
Which code segment should you add？（）

单项选择题You are creating a Windows Forms application by using the .NET Framework 3.5  The application requires a form to display a clock.You need to create a circular form to display the clock. Which code segment should you use？（）

A.A
B.B
C.C
D.D

单项选择题YouarecreatingaWindowsapplicationbyusingthe.NETFramework3.5.YoucreateaninstanceoftheBackgroundWorkercomponentnamedbackgroundWorker1toasynchronouslyprocesstimeconsumingreportsintheapplication.Youwritethefollowingcodesegmentintheapplication（Linenumbersareincludedforreferenceonly.） Youneedtowriteacodesegmentthatreportstotheapplicationwhenthebackgroundprocessdetectsanyofthefollowingactions： （1）Anexceptionisthrown （2）Theprocessiscancelled （3）Theprocessissuccessfullycompleted Whichcodesegmentshouldyouinsert？（）

A.A
B.B
C.C
D.D

单项选择题You are creating a Windows application by using the .NET Framework 3.5.You plan to create a form that might result in a timeconsuming operation.You use the QueueUserWorkItem method and a Label control named lblResult.You need to update the users by using the lblResult control when the process has completed the operation. Which code segment should you use？（）

A.A
B.B
C.C
D.D

单项选择题You are creating a Windows Forms application for a courier company by using the .NET Framework 3.5.You create a form that allows customers to track the progress of their shipments.The form contains the following elements：  （1）A text box named txtTN that allows users to enter a tracking number.  （2）An ErrorProvider control named ErrorProvider1 that informs users of an invalid tracking number.  （3）A function named ValidTrackingNumber that validates tracking numbers.   You need to ensure that the txtTN text box is validated.   Which code segment should you use？（）

A.A
B.B
C.C
D.D

单项选择题YouarecreatingaWindowsFormsapplicationbyusingthe.NETFramework3.5.Youhaveresourcefilesinfivedifferentlanguages.Youneedtotesttheapplicationineachlanguage.Whatshouldyoudo？（）

A.Set the CurrentCulture property explicitly to the respective culture for each language.
B.Set the CurrentCulture property explicitly to IsNeutralCulture for each language.
C.Set the CurrentUICulture property explicitly to IsNeutralCulture for each language.
D.Set the CurrentUICulture property explicitly to the respective culture for each language.