Extract n words from string using Perl - perl

Question

i have a text containing sentences in each line, and in front of each word its lemmetize form exemple:
he "he" went "go" to "to" school "school" with "with" his "his" freinds "freind"
i would like to extract for example three by three word in in each line. The result seems like this:
he "he" went "go" to "to" \n
went "go" to "to" school "school" \n
to "to" school "school" with "with" \n
school "school" with "with" his "his" \n
with "with" his "his" freinds "freind" \n
I'd like to do this using Perl.

Answer 1

thank you all for your helps, i found a solution, it works, but it's in dirty code i think, that's why i asked this question, to find a better solution, the awk solution seems great but the result not like i look,
This is the solution i fixed the window at 7 words and in front of each word it's POS and it's lemmetized form:
he "he" "PRO" went "go" "V" to "to" "PREP" school "school" "N" ...
open(F,"/home/file.txt")||die "error";
my $string;
while($ligne = <F> ) {
my #val = split(/ /, $ligne);
my $long=$#val;
for($i=0; $i<$long;$i+=3){
$string="$val[$i] $val[$i+1] $val[$i+2] $val[$i+3] $val[$i+4] $val[$i+5] $val[$i+6] $val[$i+7] $val[$i+8] $val[$i+9] $val[$i+10] $val[$i+11] $val[$i+12] $val[$i+13] $val[$i+14] $val[$i+15] $val[$i+16] $val[$i+17] $val[$i+18] $val[$i+19] $val[$i+20]";
my #val2 = split(/ /, $string);
my $long2=$#val2;
if($long2 >19){ #if length superior at 19, (3*7)
print FILEOUT "$string\n";
$string="";
}
}
}

Answer 2

This script starts by reading the entire line as an array of words (#words) and then uses an #aux array as a FIFO... discarding the first 2 elements at each pass and keeping the FIFO size always 6 itens... then, reapeat while there are words in the #words array:
#!/usr/bin/perl
use strict;
my $file = 'file.txt';
open(F,$file)||die "error";
my #aux;
while(<F>) {
my #words = split /\s+/;
while($#words >= 0) {
while($#aux < 5 && $#words >= 0) {
my $a = shift #words;
push #aux, $a;
}
print ((join " ", #aux)."\n");
shift #aux;
shift #aux;
}
}