验证码地址： http://www.teacher.com.cn/ImageCode.aspx

调用方式： DownNetFile "http://www.teacher.com.cn/ImageCode.aspx", "h:\123.jpeg"

Private Sub DownNetFile(ByVal nUrl As String, ByVal nFile As String)
     Dim XmlHttp, B() As Byte
     Set XmlHttp = CreateObject("Microsoft.XMLHTTP")
     XmlHttp.Open "GET", nUrl, False
     XmlHttp.Send
     If XmlHttp.ReadyState = 4 Then
         B() = XmlHttp.ResponseBody
         Open nFile For Binary As #1
         Put #1, , B()
         Close #1
     End If
     Set XmlHttp = Nothing
End Sub