function check(){

// Проверка названия компании
   per=feedback.company_name.value;
   if (per=="") {
     alert(" You have not specified the Company name.");
     document.feedback.company_name.focus();
     return false;}
// Проверка адресной части e-mail
  per=feedback.email.value;
   if (per=="") {
     alert(" You have not specified the e-mail address.");
     document.feedback.email.focus();
     return false;}
   else{
     if (feedback.email.value.indexOf('@', 0) == -1) {
        alert(' Symbol "@" is absent in your e-mail address. Please check it up.');
        document.feedback.email.focus();
        return false;}
    }
//почтовый адрес
  per=feedback.postal_adr.value;
   if (per=="") {
     alert(" You have not specified the Postal address.");
     document.feedback.postal_adr.focus();
     return false;}
// Проверка ввода статуса
  per=feedback.your_status.value;
  per1=feedback.other_status.value;
  switch ( per ) {
    case  "NO":
      if (per1=="") {
        alert(" You have not specified your status");
        document.feedback.your_status.focus();
        return false;}
      break;
   default :
      if (per1!="") {
        alert('You filled in two different statuses.');
        document.feedback.other_status.focus();
        return false;}
 }
// Проверка ввода видов услуг
  kolv=0;
  if (feedback.trademark.checked) kolv++;
  if (feedback.patent.checked) kolv++;
  if (feedback.design.checked) kolv++;
  if (kolv==0) {
    alert(" You have not specified any of our services.");
        document.feedback.trademark.focus();
        return false;}
 return true;
}