c:\@Work\Perl\monks>perl -wMstrict -le
"my $s = 'CCHHHCHHCHC';
 print qq{'$s'};
 ;;
 $s =~ s/(\w) (?!\1). \1/$1$1$1/xgi;
 print qq{'$s'};
"
'CCHHHCHHCHC'
'CCHHHHHHHHC'