'index.html' =~ /\.html?/; '<bob@gmail.com>' =~ /\w+/; 'Up to 50% off' =~ /\d+/; 'Space 1999' =~ /\w\d*/; 'hippopotamus' =~ /p.p/; 'disgruntled' =~ /g.*/; 'in a tight spot' =~ /\w{3,4}/;