#!/usr/bin/perl -l
use strict; use warnings;

my %words;
@words{map tr/a-z//cdr, <DATA>} = ();

for (sort keys %words) # sort optional
  {
  exists $words{"$`s$'"} and print "$_ $`s$'" while /r/g;
  }
__DATA__
cases
carer
caser
cares
bare
mare
base
case
bust
burt
bent
sat
rat
bat
matter
mattes
pat