function bt(){
if(document.getElementById("dst").value == "ja"){
document.getElementById("secondRead").style.display = "block"; 
}else if(document.getElementById("dst").value != "ja"){
document.getElementById("secondRead").style.display = "none"; 
}

if(document.getElementById("src").value != "ja"){
document.getElementById("firstRead").style.display = "none"; 
}else if(document.getElementById("src").value == "ja"){
document.getElementById("firstRead").style.display = "block"; 
}

}