How to write multiple CSS class names in single "echo" ?

[Pradeep_Chinna]

php:

 

...bla bla bla....

 

echo "<tr class=\"top bottom row\">   // This is perfectly wrong declaration. please tel me what is actually correct one to declare multiple                                                                  css class names here ?? //

         <td>Date</td> 

         <td>Name</td>

         <td>Purpose</td> 

         </tr> ";

 

CSS:

 

tr.top td { border-top: thin solid blue; }

tr.bottom td { border-bottom: thin solid green; }

tr.row td:first-child { border-left: thin solid red; }

tr.row td:last-child { border-right: thin solid black; }

 

please help me out...

in Advance, Thank you.