How to set a <b>gray background</b> for the <b>fir

How to set a gray background for the first and third rows only?


<table>

    <tr>

         <td>name</td>

         <td>one</td>    

    </tr>

     <tr>

         <td>name</td>

         <td>two</td>    

    </tr>

     <tr>

         <td>name</td>

         <td>three</td>  
  
    </tr>

     <tr>

         <td>name</td>

         <td>four</td>   
 
    </tr>

</table>