You are creating a Windows Forms application by using the .NET Framework 3.5. You plan to modify a list of orders within a DataGridView control in the application. You need to ensure that a value is required in the first column of the grid control. 
Which code segment should you use？（）

单项选择题You are creating a multiple document interface （ MDI） application by using the .NET Framework 3.5 . You configure the frmParent form to be an MDI parent.You write the following code segment （Line numbers are included for reference only.） You need to associate and display the frmChild form and the frmParent form.   Which code segment should you add？（）

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

单项选择题You are creating a Windows Forms application by using the .NET.Framework 3.5. You create a new form in your application.You add a SplitContainer control named spcFrame to the form.  The SplitContainer control has two SplitterPanel controls named Panel1 and Panel2. You are configuring the SplitContainer control to define the layout of the form. You need to ensure that the following requirements are met：  （1）The initial distance from the left edge of the spcFrame splitter is set to 200 pixels  （2）The size of the Panel2 SplitterPanel remains unchanged when the form is resized    Which code segment should you use？（）

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

单项选择题YouarecreatingaWindowsFormsapplicationbyusingthe.NETFramework3.5.Youcreateanewformintheapplication.YouaddaContextMenuStripcontrolnameddctxMenutotheform.YouhaveauserdefinedclassnamedCustomControl.Youwritethefollowingcodesegmentintheapplication（Linenumbersareincludedforreferenceonly） CustomControlmyControl=newCustomControl（）； YouneedtoensurethataninstanceofCustomControlisdisplayedontheformasatoplevelitemofthectxMenucontrol. Whichcodesegmentshouldyouadd？（）

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

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