if (1)
 {my $data = "this is a test";
  my $expression_text = "(.*)es";
  $data =~  $expression_text;  say "1: $1";
  $data =~ /$expression_text/; say "2: $1";
 }
if (1)
 {my $data = "this is a test";
  my $expression_text = qr(es);
  $data =~  $expression_text;      say "3: $data";
  $data =~ s/$expression_text/dd/; say "4: $data";
 }