.alignR{text-align:right}
居右:<td align="alignR"></td>
<style>div {position:absolute width:200px height:400px}
div.left {left:0 background-color:red}
div.center {left:50% margin-left:-100px background-color:green}
div.right {right:0 background-color:blue}
</style>
<div class="left">左</div>
<div class="center">中</div>
<div class="right">右</div>