1. SVG Shapes
   1.矩形 <rect>

      <rect x="50" y="20" width="150" height="150" style="fill:red;stroke:black;stroke-width:5;opacity:0.5"/>
      
      
   

2. <circle>

<circle cx="100" cy="50" r="40" stroke="black" stroke-width="2" fill="red"/>

1. <line>

<line x1="0" y1="0" x2="200" y2="200"
  style="stroke:rgb(255,0,0);stroke-width:2"/>