$_='Us ? The bus usually waits for us, unless the driver forgets us.';


##</code><code>##

$_='Us ? The bus usually waits for us, unless the driver forgets us.';
print "$_\n";
s/\b([Uu])s(\W)/chr(ord($1)-1).hem.$2/eg;
print "$_\n";


##</code><code>##

$_='Us? The bus usually waits for us, unless the driver forgets us.';
print "$_\n";
s/\bus\b/them/ig;
print "$_\n";