vb WebBrowser如何取class的值

如何取得表单里class的值?
<input type="button" value="修改" class="wns_btn_2" onClick="doModifyRedirect('http://china.kkkkk.com/offer/offer_post.htm?offer_id=540799796&edit=true&done_url=http%3A%2F%2Fchina.kkkkk.com%2Foffer%2Fmanage.htm%3Fshow_type%3Dvalid%26keywords%3D%26type%3D%26trade_type%3Dnull%26is_sms_repost_offer%3Dnull%26is_trade_offer%3Dnull%26offer_group%3D0%26page_size%3D20%26un_need_link%3DN%26begin_page%3D1')" onMouseDown="return aliclick(this,'?tracelog=gl_onweb_modify');" />
<input type="button" onClick="javascript:doRepost(540799796)" onMouseDown="return aliclick(this,'?tracelog=gl_onweb_repost');" value="重发"  class="wns_btn_2" />
<input type="button" value="修改" class="wns_btn_2" onClick="doModifyRedirect('http://china.kkkkk.com/offer/offer_post.htm?offer_id=540810348&edit=true&done_url=http%3A%2F%2Fchina.kkkkk.com%2Foffer%2Fmanage.htm%3Fshow_type%3Dvalid%26keywords%3D%26type%3D%26trade_type%3Dnull%26is_sms_repost_offer%3Dnull%26is_trade_offer%3Dnull%26offer_group%3D0%26page_size%3D20%26un_need_link%3DN%26begin_page%3D1')" onMouseDown="return aliclick(this,'?tracelog=gl_onweb_modify');" />
 <input type="button" onClick="javascript:doRepost(540810348)" onMouseDown="return aliclick(this,'?tracelog=gl_onweb_repost');" value="重发"  class="wns_btn_2" /><input type="button" value="修改" class="wns_btn_2" onClick="doModifyRedirect('http://china.kkkkk.com/offer/offer_post.htm?offer_id=548739282&edit=true&done_url=http%3A%2F%2Fchina.kkkkk.com%2Foffer%2Fmanage.htm%3Fshow_type%3Dvalid%26keywords%3D%26type%3D%26trade_type%3Dnull%26is_sms_repost_offer%3Dnull%26is_trade_offer%3Dnull%26offer_group%3D0%26page_size%3D20%26un_need_link%3DN%26begin_page%3D1')" onMouseDown="return aliclick(this,'?tracelog=gl_onweb_modify');" />
    <input type="button" onClick="javascript:doRepost(548739282)" onMouseDown="return aliclick(this,'?tracelog=gl_onweb_repost');" value="重发"  class="wns_btn_2" />
    
    
    
    <input type="button" value="修改" class="wns_btn_2" onclick="doModifyRedirect('http://china.kkkkk.com/offer/offer_post.htm?offer_id=513630875&edit=true&done_url=http%3A%2F%2Fchina.kkkkk.com%2Foffer%2Fmanage.htm%3Ftracelog%3Dmyali_menu_manageoffer')" onMouseDown="return aliclick(this,'?tracelog=gl_onweb_modify');" />
   
 <input type="button" value="重发"  class="wns_btn_2_disable" disabled title="此信息已重发，需要再次重发请明天进行"></input>
  </td>
  <td class="wns_list_main_status"> 已重发</br>
  </td>
</tr>