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<html><head><script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script><script>$(document).ready(function(){ $(".intro, .demo, .end").css("background-color", "yellow");});</script></head><body><h1>Welcome to My Homepage</h1><p class="intro">This paragraph has class "intro".</p><p>This is a paragraph.</p><p class="demo">This paragraph has class "demo".</p><p>This is another paragraph.</p><p class="end">This paragraph has class "end".</p></body></html>