Add all table names of my database to combo Box

Question

public void show()
{
       ds = new DataSet();
       ada = new SqlDataAdapter("select * from    sys.tables", conn);
       //ada = new SqlDataAdapter("select * from emp",    conn);
       //ds = new DataSet();
       ada.Fill(ds);
}  

private void Form1_Load(object sender, EventArgs    e)
{
       conn = new SqlConnection(@"Data Source=ASHISH-PC\SQLEXPRESS; initial    catalog=ashish; integrated security=true");
       show();
       foreach (DataTable dt in ds.Tables)
       {
           comboBox1.Items.Add(dt.TableName[0]);
       }
}