function check_value() 
{
	if (form1.subject.value == '')
	 {
		window.alert("主题不能为空！");
        form1.subject.focus();
		return false;
	}
	if (form1.content.value == '')
	 {
		window.alert("留言信息不能为空！");
        form1.content.focus();
		return false;
	}

	if (form1.name.value == '')
	 {
		window.alert("姓名不能为空！");
        form1.name.focus();
		return false;
	}
	if (form1.tel.value == '')
	 {
		window.alert("电话不能为空！");
        form1.tel.focus();
		return false;
	}
	if (form1.email.value == '')
	 {
		window.alert("email不能为空！");
        form1.email.focus();
		return false;
	}

	   document.form1.submit();

       return true;

}