<xsl:template match="control">
       <select onchange="this.form.ack_content.value=this.text"
    multiple="" style="width: 80px;" size="6" name="">
           <xsl:for-each select="operate">
               <option>
                   <xsl:value-of select="reason" />
               </option>
           </xsl:for-each>
       </select>
    </xsl:template>想在option中插入value="<xsl:valueof ***>"的话要怎么做?