function moveover1(){
document.getElementById('PictureBox').src=document.getElementById('tn1').src;
}
function moveover2(){
document.getElementById('PictureBox').src=document.getElementById('tn2').src;
}
function moveover3(){
document.getElementById('PictureBox').src=document.getElementById('tn3').src;
}
function moveover4(){
document.getElementById('PictureBox').src=document.getElementById('tn4').src;
}
function moveback(){
document.getElementById('PictureBox').src=document.getElementById('tn').src;
}