<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>文字修饰标记</title> </head> <body> <u> 下划线 <i> 倾斜下划线 <b>加粗倾斜下划线</b> </i> </u> <h1> H<sub>2</sub>0<br /> X<sup>2</sup>+Y<sup>2</sup>=Z<sup>2</sup> </h1> </body> </html>
