求大佬指教，怎么简化下面的代码

有没有大佬帮我简化下面的代码：

  menu_li[0].onmouseover=function()
      {startMove( under_line[0],{width:100});};
 
       
      menu_li[0].onmouseout=function()
      {startMove( under_line[0],{width:0});};
     
       menu_li[1].onmouseover=function()
      {startMove( under_line[1],{width:100});};
 
       
      menu_li[1].onmouseout=function()
      {startMove( under_line[1],{width:0});};
       
    menu_li[2].onmouseover=function()
      {startMove( under_line[2],{width:100});};
 
       
      menu_li[2].onmouseout=function()
      {startMove( under_line[2],{width:0});};
     menu_li[3].onmouseover=function()
      {startMove( under_line[3],{width:100});};
 
       
      menu_li[3].onmouseout=function()
      {startMove( under_line[3],{width:0});};
        menu_li[4].onmouseover=function()
      {startMove( under_line[4],{width:100});};
 
       
      menu_li[4].onmouseout=function()
      {startMove( under_line[4],{width:0});};