var c=30;
var t
;
function timedCount(){
document.getElementById( "timer").innerHTML=c+"秒后可重新发送" ;
c-- ;
if(c<0){
clearTimeout(t) ;
document.getElementById('send' ).style.display="block";
document.getElementById('time' ).style.display="none";
c=30;
return;
}
t=setTimeout( "timedCount()",1000)
;
}