<html><head><script src="https://ajax.aspnetcdn.com/ajax/jQuery/jquery-3.5.1.min.js"></script><script> $(document).ready(function(){ $("#flip").click(function(){ $("#panel").slideDown("slow"); });});</script><style> #panel, #flip { padding: 5px; text-align: center; background-color: #e5eecc; border: solid 1px #c3c3c3;}#panel { padding: 50px; display: none;}</style></head><body> <div id="flip">点击下拉面板</div><div id="panel">Hello world!</div></body></html>