让table具有滚动条(ZZ:http://www.blogjava.net/leekiang/archive/2007/09/24/147851.html)
用一个div将table 套住,把层的宽和高都设为定长,
<div style="overflow-y:scroll;width:100%;height:100%">
<table>
</table>
</div>
overflow-y不要设置为visible
<div style="overflow-y:scroll;width:100%;height:100%">
<table>
</table>
</div>
overflow-y不要设置为visible