要求：将下面的三行分页水平居中。

*{
       margin: 0;    padding: 0;}ul{
       list-style: none;}.wrap{
       width: 500px;    height: 100px;    background: #000;}.test{
       padding-top: 10px;    float: left;    clear: both;    position: relative;    left: 50%;}.test li{
       float: left;    margin-right: 5px;    position: relative;    left: -50%;}.test li a{
       float: left;    text-decoration: none;    width: 20px;    text-align: center;    line-height: 20px;    height: 20px;    background: #fff;}

     
        
      
            
       
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