1. (2017高一上·台州期末) 现有如下Visual Basic程序段：

Private Sub Command1_Click()

    Dim a(-1 To 8) As Integer

    Dim i As Integer

    For i = -1 To 8

        a(i) = i * i

    Next i

    Print a(i)

End Sub

运行程序，单击命令按钮Command1后，出现的错误提示可能是（   ）