img1=new Image();
img1.src ="images/menu_b_01.gif";
img2=new Image();
img2.src ="images/menu_b_02.gif";
img3=new Image();
img3.src ="images/menu_b_03.gif";
img4=new Image();
img4.src ="images/menu_b_04.gif";
img5=new Image();
img5.src ="images/menu_b_05.gif";
img6=new Image();
img6.src ="images/menu_b_06.gif";
img7=new Image();
img7.src ="images/menu_b_07.gif";
img8=new Image();
img8.src ="images/menu_b_08.gif";
img9=new Image();
img9.src ="images/menu_b_09.gif";


function preLoad(){
  var imgCount = 9;//需要预先加载10张图片
  var images = new Array();
  for (var i=0;i<imgCount;i++){
    images[i] = new Image();
    images[i].src ="images/menu_b_0"+ (i+1) + ".gif";
  }
}