单项选择题

下面程序的输出结果是( )
Private Sub Command1_Click()
Ch$="ABCDEF"
proc ch:Print ch
End Sub
Private Sub proc(ch As String)
s=" "
For k=Len(ch)To 1 Step-1
s=s＆Mid(ch,k,1)
Next k
ch=s
End Sub

点击查看答案&解析