//取html中全部 select 的 name
Regex reg_name = new Regex(@"(?<=<select name=/"").*?(?=/"")");

//取html中全部<select>項的值
Regex reg_select = new Regex("(?is)<select name=*.*?>]*.*?</select>");

//取html中一個 select name 等于"Status"的值
Regex status = new Regex(@"(?is)<select name=/""status/"">]*.*?</select>");

string strDoc = （你的html）;

//取html中一個下拉菜單 select name 等于"Status"的中值
Regex status = new Regex(@"(?is)<select name=/""status/"">]*.*?</select>");
MatchCollection mc_status = status.Matches(strDoc);
getSelectOptions(mc_status, cmbStatus);

/// <summary>
/// 取select對列表復制
/// </summary>
/// <param name="selected"></param>
/// <param name="cmb"></param>
void getSelectOptions(MatchCollection selected, ComboBox cmb)
{
    if (selected.Count < 1)
        return;
    txtValues.Text = "";
    txtValues.Text = selected[0].Value.Replace("</option>", Environment.NewLine);
    string tmpTxt = "";
    foreach (string s in txtValues.Lines)
    {
        if (s == "")
            continue;
        string a = "";
        a = s.Replace("/"", "").Replace("<option value=/"", "");
        int x = a.LastIndexOf(">");
        tmpTxt += a.Substring(x + 1) + Environment.NewLine;
    }
    txtValues.Text = tmpTxt.Trim();
    cmb.Items.Clear();
    cmb.Items.AddRange(txtValues.Lines);
    cmb.SelectedIndex = 0;
    cmb.Size = cmb.PreferredSize;
}