设有如下通用过程:Public Function Fun (xStr As String) As StringDim tStr As String,strL As

设有如下通用过程：Public Function Fun (xStr As String) As String Dim tStr As String，strL As Integer tStr=-" " strL=Len(xStr) i=strL/2 Do Whilei＜=strL tStr=tStr &id(xStr,i+1，1) i=i+1 Loop Fun=tStr & tStrEnd Function 在窗体上画—个名称为Text1的文本框和—个名称为Command1的命令按钮，然后编写如下的事件过程：Private Sub Command1_ Click() Dim S1 String S1="ABCDEF" Text1.Text=LCase(Fun(S1))End Sub 程序运行后，单击命令按钮，文本框中显示的是 ______。

A．ABCDEF

B．abcdef

C．defdef

D．defabc