$a=array('fruits'=>array('a'=>'orange','b'=>'grape',c=>'apple'),
 'numbers'=>array(1,2,3,4,5,6),
 'holes'=>array('first',5=>'second','third')
 );
//第一种：
foreach($a as $list=>$things){
 if(is_array($things)){
 foreach($things as $newlist=>$counter){
 echo "key:".$newlist."<br/>"."value:".$counter."<br/>";
 }
}
}
//第二种:
function MulitarraytoSingle($array){
  $temp=array();
  if(is_array($array)){
   foreach ($array as $key=>$value )
   {
    if(is_array($value)){
     MulitarraytoSingle($value);
    }
    else{
     $temp[]=$value;
    }
   }
  }
}