使用CSS：nth-of-type(n)选择器来设置作为其父级的第n个<p>元素的每个<p>元素的样式。您可以尝试运行以下代码来实现：nth-of-type(n)选择器
<!DOCTYPE html>
<html>
<head>
<style>
p:nth-of-type(2) {
background: yellow;
}
</style>
</head>
<body>
<p>This is demo text 1.</p>
<p>This is demo text 2.</p>
<p>This is demo text 3.</p>
<p>This is demo text 4.</p>
</body>
</html>