html5 - 为什么svg标签里面的内容只有用webstorm链接的浏览器打开可以看见,直接打开原文件（.html文件）就不显示了
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg xmlns="http://www.w3.org/2000/svg&qu...
<symbol id="icon-captions-off" viewBox="0 0 18 18">
<path d="M1 2c-.552 0-1 .448-1 1v12c0 .552.448 1 1 1h16c.552 0 1-.448 1-1V3c0-.552-.448-1-1-1H1zm1 12V4h14v10H2z"/>
</symbol><symbol id="icon-volume" viewBox="0 0 18 18"><path d="M10.214 2c-.11 0-.225.032-.334.1L5.832 4.91C5.75 4.97 5.65 5 5.55 5H1.995C1.446 5 1 5.448 1 6v6c0 .552.446 1 .996 1H5.55c.1 0 .2.03.282.09L9.88 15.9c.11.068.223.1.334.1.392 0 .747-.4.747-.95V2.95c0-.55-.354-.95-.746-.95zM8.97 12.834L6.58 11.177c-.166-.115-.364-.178-.566-.178H3.49c-.274 0-.497-.225-.497-.5v-3c0-.277.223-.5.498-.5h2.526c.202 0 .4-.063.566-.18L8.97 5.165v7.67zM16.934 8.8c-.086-1.75-1.514-2.992-2.507-3.65-.47-.312-1.094-.122-1.325.408l-.038.086c-.188.43-.045.94.336 1.194.706.473 1.586 1.247 1.624 2.065.032.676-.553 1.468-1.663 2.27-.397.288-.528.84-.284 1.275l.042.075c.266.475.866.624 1.3.312 1.74-1.25 2.586-2.606 2.516-4.037z"/></symbol></svg>
2.在webstorm中调用会在网页中显示,直接打开为什么不显示?
