PHP在元素之间回显逗号

My code pulls certain elements from an html table and lists them:

foreach($html->find('tr[align=center]') as $e)
echo strip_tags($e->innertext) . '<br>';

The output looks like this:

OPEN 91212 ACCY 2001 12 Intro Financial Accounting 3.00 Zou, Y 1957 E B12 TR02:20PM - 03:35PM 01/13/14 - 04/28/14 

Here is the HTML table these items are being pulled from:

 <table width="100%"  border="0" cellspacing="1" cellpadding="0" bgcolor="#006699">
    <tr align="center" class="tableRow1Font">
        <td width="7%">WAITLIST</td>
        <td width="5%">91630</td>
        <td width="11%">ACCY <A HREF="http://www.gwu.edu/~bulletin/ugrad/accy.html#2001" target="_blank">2001</A>
        </td>
        <td width="5%">10</td>
        <td width="16%">Intro Financial Accounting</td>
        <td width="6%">3.00</td>
        <td width="8%"> Zou, Y</td>
        <td width="8%"><A HREF="http://www.gwu.edu/~map/building.cfm?BLDG=DUQUES" target="_blank" >DUQUES</a> 251</td>
        <td width="13%">TR<br>09:35AM - 10:50AM</td>
        <td width="14%">
            01/13/14 - 04/28/14
        </td>
        <td width="7%">

        </td>
    </tr>

How could I change my code to echo a comma to separate each element? I want it to look like this:

OPEN, 91212, ACCY 2001, 12, Intro Financial Accounting, 3.00, Zou, Y, 1957 E B12, TR02:20PM - 03:35PM, 01/13/14 - 04/28/14 

Try

$html->find('tr[align=center] td') 

Instead to loop through each td, and replace your br tag with a comma

echo strip_tags($e->innertext) . ', ';

foreach($html->find('tr[align=center]') as $e){ 
     $str .= strip_tags($e->innertext). ",";
}
$str = trim($str, ",");//delete last ","
echo $str;