在控件的keyPress事件中，添加如下代码：
Private Sub t2008a_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles t2008a.KeyPress、
If Not (Char.IsDigit(e.KeyChar) Or Char.IsControl(e.KeyChar)) Then
e.Handled = True
End If
End Sub