function CheckForm() { 
 var name = comment_form.first.value;
 if (name == "") { 
    alert("Please enter your first name."); 
    comment_form.first.focus();
    return false; 
}
 var name = comment_form.last.value;
 if (name == "") { 
    alert("Please enter your last name."); 
    comment_form.last.focus();
    return false; 
}
 if (comment_form.email.value.indexOf ('@',0) == -1 ||comment_form.email.value.indexOf ('.',0) == -1){
    alert ("The email address you entered is not valid. Please re-enter your email address.")
    comment_form.email.focus();
    valid = false; 
    return false ;
}
 var name = comment_form.comments.value;
 if (name == "") { 
    alert("You have not entered any comments."); 
    comment_form.comments.focus();
    return false; 
}
 return true; 
}