blueberry: It's good that you've frankly stated that your OP is a homework question, something that I'm sure many of us suspected. However, please realize that the Monastery is not a homework completion service.

I and many others will be glad to provide guidance, and GotToBTru and davido have already given you some very valuable advice and hints. Please see CountZero's reply if you want to see some code with Adult Content (just for reference of course). Also, please consult your course materials.

Again, please be careful to post code in  <code> ... </code> tags as has been suggested. Your OP has been cleaned up (whether by you or someone else I know not), but other replies of yours are still almost unreadable, and the Monks get very grumpy if they must do a lot of work in order to provide free advice!

Well, I wouldn't call CPAN "adult content", I think it's at least (or is that "at most"?) PG-13 or even G-rated :-)

"mature", or "professional" are more appropriate words.

Anyway, to stay on topic, here my stab at it (of course, for irregular verbs, the Lingua::EN modules are better than List::MoreUtils):

#!/usr/bin/env perl
use 5.011; # implies strict
use warnings;
use List::MoreUtils 'pairwise'; # this is it

my @pronouns = qw(I thou he/she/it we you they);
my @endings = ('', 'st', 's', '', '', '');
print "predicate?\n";
my $predicate = <>;
my ($verb, $rest) = split ' ', $predicate, 2;
pairwise {
    no warnings 'once';
    print "$a $verb$b $rest"; # no \n because no chomp
} @pronouns, @endings;
[download]

A test with Input want a beer gives

I want a beer
thou wantst a beer
he/she/it wants a beer
we want a beer
you want a beer
they want a beer
[download]