php如何使用echo输出常量+变量?

Question

//替换图片Alt为文档标题
$this->Fields['body'] = str_ireplace(array('alt=""','alt=\'\''),'',$this->Fields['body']);
$this->Fields['body'] = preg_replace("@ [\s]{0,}alt[\s]{0,}=[\"'\s]{0,}[\s\S]{0,}[\"'\s] @isU"," ",$this->Fields['body']);
$this->Fields['body'] = str_ireplace("<img " ,"<img alt='".$this->Fields['title']."' ",$this->Fields['body']);

echo '<script lanuage="javascript">';
echo 'alert("？");'; //输出$this->Fields['body']
echo '</script>';

这里输出如何写？
又比如说这个
$body = str_ireplace(array('alt=""','alt=\'\''),'',$body); 
echo '<script lanuage="javascript">';
echo 'alert("?");'; //输出$body,PHP中的连接符是什么？
echo '</script>';