function showimg1(){
document.area1.src = "images/index/tab01a.jpg";
document.area2.src = "images/index/tab02b.jpg";
document.area3.src = "images/index/tab03b.jpg";
}

function showimg2(){
document.area1.src = "images/index/tab01b.jpg";
document.area2.src = "images/index/tab02a.jpg";
document.area3.src = "images/index/tab03b.jpg";
}

function showimg3(){
document.area1.src = "images/index/tab01b.jpg";
document.area2.src = "images/index/tab02b.jpg";
document.area3.src = "images/index/tab03a.jpg";
}