< div id = " list " >
 < ul >
  < li >aaaaaaaaaaaaaaaaaaaa < / li >
  < li > bbbbbbbbbbbbbbbbb< / li >
  < li > cccccccccccccccccccccc< / li >
 < /ul >
< /div >

#list {width:320px;overflow:hidden;}
#list ul {width:330px;}
#list li {width:100px; float:left;margin:0 10px 0 0;}