多为数组转换成一维-递归

function array_multi2single($array,&$rs = array()){
    foreach($array as $value){
        if(is_array($value)){
            array_multi2single($value, $rs);
        }
        else
        $rs[]=$value;
    }
}

$array=array("1"=>array("A","B","C",array("D","E")),"2"=>array("F","G","H","I"));
array_multi2single($array, $rs);

print_r($rs);