<?php

foreach($array as $k=>$value1 ){
 if(is_string($value1) ) //on place les chaîne de caractères dans le tableau $array1
  $array1[$k] = $value1 ;
 if(is_array( $value1 ) ) {  //l'élement du tableau est lui même un tableau alors on peut le parcourir
foreach($value1 as $key=>$value2){
  $array2[$key] = $value2;
}
}
}

echo "<pre>";
var_dump($array1);
echo "</pre>";


echo "<pre>";
var_dump($array2);
echo "</pre>";

?>

array(14) { [0]=> string(62) "avancer" [1]=> string(63) "echapper" [2]=> string(61) "ramper" [3]=> string(62) "chasser" [4]=> string(62) "inserer" [5]=> string(60) "riper" [6]=> string(61) "couler" [7]=> string(65) "introduire" [8]=> string(60) "skier" [9]=> string(64) "coulisser" [10]=> string(61) "mettre" [11]=> string(61) "tomber" [12]=> string(62) "deraper" [13]=> string(62) "patiner" } array(23) { [0]=> string(63) "absorber" [1]=> string(60) "laper" [2]=> string(63) "se-taper" [3]=> string(62) "arroser" [4]=> string(60) "lever" [5]=> string(62) "siffler" [6]=> string(61) "avaler" [7]=> string(62) "picoler" [8]=> string(62) "siroter" [9]=> string(65) "biberonner" [10]=> string(61) "pomper" [11]=> string(60) "subir" [12]=> string(64) "consommer" [13]=> string(65) "s-abreuver" [14]=> string(60) "sucer" [15]=> string(62) "ecluser" [16]=> string(63) "savourer" [17]=> string(63) "trinquer" [18]=> string(71) "etancher-sa-soif" [19]=> string(68) "se-desalterer" [20]=> string(60) "vider" [21]=> string(65) "ingurgiter" [22]=> string(68) "se-rafraichir" } array(1) { [0]=> string(59) "plus" } array(24) { [0]=> string(61) "abuser" [1]=> string(63) "capturer" [2]=> string(62) "prendre" [3]=> string(65) "admonester" [4]=> string(61) "choper" [5]=> string(66) "reprimander" [6]=> string(63) "agripper" [7]=> string(65) "contracter" [8]=> string(64) "reprocher" [9]=> string(64) "atteindre" [10]=> string(60) "duper" [11]=> string(61) "saisir" [12]=> string(60) "avoir" [13]=> string(62) "gronder" [14]=> string(64) "s-emparer" [15]=> string(61) "berner" [16]=> string(61) "happer" [17]=> string(64) "sermonner" [18]=> string(61) "blamer" [19]=> string(62) "leurrer" [20]=> string(65) "subtiliser" [21]=> string(61) "capter" [22]=> string(64) "mystifier" [23]=> string(62) "tromper" }