if(document.images) {
 var imgs = new Array();
 imgs[0] = new Image();  imgs[0].src = "img/top1.gif"; 
 imgs[1] = new Image();  imgs[1].src = "img/top2.gif";
 imgs[2] = new Image();  imgs[2].src = "img/setumei1.gif";
 imgs[3] = new Image();  imgs[3].src = "img/setumei2.gif";
 imgs[4] = new Image();  imgs[4].src = "img/nomikata1.gif"; 
 imgs[5] = new Image();  imgs[5].src = "img/nomikata2.gif";
 imgs[6] = new Image();  imgs[6].src = "img/kounyuu1.gif"; 
 imgs[7] = new Image();  imgs[7].src = "img/kounyuu2.gif"; 
 imgs[8] = new Image();  imgs[8].src = "img/taiken1.gif";
 imgs[9] = new Image();  imgs[9].src = "img/taiken2.gif";
 imgs[10] = new Image();  imgs[10].src = "img/qa1.gif"; 
 imgs[11] = new Image();  imgs[11].src = "img/qa2.gif";
 imgs[12] = new Image();  imgs[12].src = "img/toi1.gif";
 imgs[13] = new Image();  imgs[13].src = "img/toi2.gif";
 imgs[14] = new Image();  imgs[14].src = "img/gaiyou1.gif"; 
 imgs[15] = new Image();  imgs[15].src = "img/gaiyou2.gif";
 imgs[16] = new Image();  imgs[16].src = "img/tokutei1.gif";
 imgs[17] = new Image();  imgs[17].src = "img/tokutei2.gif";
 imgs[18] = new Image();  imgs[18].src = "img/b_obsrvtn.gif"; 
 imgs[19] = new Image();  imgs[19].src = "img/b_obsrvtn2.gif";
 imgs[20] = new Image();  imgs[20].src = "img/b_dealer.gif";
 imgs[21] = new Image();  imgs[21].src = "img/b_dealer2.gif";
 imgs[22] = new Image();  imgs[22].src = "img/b_inqry.gif";
 imgs[23] = new Image();  imgs[23].src = "img/b_inqry2.gif";
}

function chgimg(id, imgname) {
 if(document.images) {
  if(imgs[imgname]) {
    document.images[id].src = imgs[imgname].src;
  }
  else {
    document.images[id].src = imgname;
  }
 }
}