var defImg;
function ImgChange(target, img){
  if(document.getElementById){
    defImg = document.getElementById(target).getAttribute("src");
    document.getElementById(target).setAttribute("src", img);
  }
}
function ImgBack(target){
  if(document.getElementById){
    document.getElementById(target).setAttribute("src",defImg);
  }
}
          function addstring() {
              document.forms[0].q.value = 'site:avail-world.co.jp ' + document.forms[0].q.value;
              return true;
          }