VBA 判断全角半角

Option Explicit
Sub N_Sample034()
    Dim a As String
    a = Application.InputBox(Prompt:="请输入一个字符")
    Select Case True
        Case a Like "[A-Z]": MsgBox "半角英文大写"
        Case a Like "[a-z]": MsgBox "半角英文小写"
        Case a Like "[Ａ-Ｚ]": MsgBox "全角英文大写"
        Case a Like "[a-z]": MsgBox "全角英文小写"
        Case a Like "[0-9]": MsgBox "半角数字"
        Case a Like "[０-９]": MsgBox "全角数字"
        Case Else: MsgBox "中文字符或者符号"
    End Select
End Sub