m/the/ .. /(\.|\?|\,)$/im

my $string = qq~I wish it was the dog that barked, 
but it wasn't. 
It was a cat.~;  
 
print $1 while ($string =~ m/(the.*[?,.])$/img);

#!/usr/bin/perl -w 
 
use strict; 
use warnings; 
 
my $file = $ARGV[0];  
 
open(INPUT, $file) 
    or die "Couldn't open $file for reading: $!\n"; 
 
while (<INPUT>) { 
	m/(it.*[?,.])$/img;    	 
	print $1; 
} 
close(INPUT);

#!/usr/bin/perl -w 
 
use strict; 
use warnings; 
 
my $file = $ARGV[0];  
 
open(INPUT, $file) 
    or die "Couldn't open $file for reading: $!\n"; 
 
print $1 while ($file =~ m/(it.*[?,.])$/img);    	 
	 
close(INPUT);

my $file = $ARGV[0] || 'test.txt';   
  
open(INPUT, $file)  
    or die "Couldn't open $file for reading: $!\n";  
  
while (<INPUT>) {  
   if (m/(the.*[?,.])$/i) { 
      print "$1\n"; 
   } 
}  
close(INPUT);

I wish it was the dog that barked, 
but it wasn't. 
It was a cat.

my $file = $ARGV[0];    
   
open(INPUT, $file)   
    or die "Couldn't open $file for reading: $!\n";   
   
while (<INPUT>) {   
   if (m/(the.*[?,.])$/i) {  
      print "$1\n";  
   }  
}   
close(INPUT);

dog that barked,

my $file = $ARGV[0];    
   
open(INPUT, $file)   
    or die "Couldn't open $file for reading: $!\n";   
   
while (<INPUT>) {   
   if (m/(it.*[?,.])$/i) {  
      print "$1\n";  
   }  
}   
close(INPUT);