function changetext1(whichcontent){
	document.getElementById(whichcontent).style.display = "block";
}
function changetext2(whichcontent, off1){
	document.getElementById(off1).style.display = "none";
	document.getElementById(whichcontent).style.display = "block";
}
function changetext3(whichcontent, off1, off2){
	document.getElementById(off1).style.display = "none";
	document.getElementById(off2).style.display = "none";
	document.getElementById(whichcontent).style.display = "block";
}