function on_ch(n){
eval("document.getElementById('text_ch"+n+"').style.display='block';");
eval("document.getElementById('offtext_ch"+n+"').style.display='block';");
}
function off_ch(n){
eval("document.getElementById('text_ch"+n+"').style.display='none';");
eval("document.getElementById('offtext_ch"+n+"').style.display='none';");
}