js checkbox

 <td style="width:68px; height: 3px" valign="middle" class="label" align="center">
                                            <asp:CheckBox ID="CheckBox5" runat="server" Text="H.B/L" />
                                        </td>

this.CheckBox5.Attributes.Add("onclick", "Set_Check31()");//H.B.L 付费条款 付款说明 运输条款

 function Set_Check31()//
{
   if(document.form1.CheckBox5.checked)//H.B/L 
  {
    document.form1.DropDownList10.disabled=false;
    document.form1.DropDownList11.disabled=false;
    //document.form1.TextBox12.value="";
  }
  else
  {
    document.form1.DropDownList10.disabled=true;
    document.form1.DropDownList11.disabled=true;
    //document.form1.Textbox12.disable=true;
     document.form1.DropDownList10.value="";
     document.form1.DropDownList11.value="";
     document.form1.TextBox12.value="";
  }
}

*******************************************************************************************

<td align="center" style="width: 68px; height: 12px">
                                            <asp:CheckBox ID="CheckBox1" runat="server" Text="危险品" Width="56px" Height="15px" />
                                        </td>     

 this.CheckBox1.Attributes.Add("onclick", "set_check_dangerous()");//危险品

function set_check_dangerous()// 
{
      if(document.form1.CheckBox1.checked)
      {
            document.form1.TextBox22.disabled=false;//但是可以Visible
            document.form1.TextBox23.disabled=false;
            document.form1.TextBox24.disabled=false;
            document.form1.TextBox29.disabled=false;
      }
      else
      {
            document.form1.TextBox22.disabled=true;
            document.form1.TextBox22.value="";
            document.form1.TextBox23.disabled=true;
            document.form1.TextBox23.value="";
            document.form1.TextBox24.disabled=true;
            document.form1.TextBox24.value="";
            document.form1.TextBox29.disabled=true;
            document.form1.TextBox29.value="";
      }
}