Granny often tells us _______ water in our daily life.[ ]

A. save

B. saving

C. to save

D. saves

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=1 Do While i<=strL/2tStr=tStr & Mid(xStr，i，1) & Mid(xStr，strL-i+1，1) i=i+1LoopFun=tStr End Function在窗体上画一个名称为Command1的命令按钮。然后编写如下的事件过程：Private Sub Command1_Click()Dim S1 As StringS1="abcdef"Print UCase(Fun(S1))End Sub程序运行后，单击命令按钮，输出结果是

A．ABCDEF

B．abcdef

C．AFBECD

D．DEFABC