How keep original value for some field when execute Edit on MVC?

Question

As you know, When we want to Modify a data, We will go to Edit page:

public ActionResult EditAdmin(int UserId)
{ 
        User user = persons.Users.Find(id);
        return View(user);
}

Then We submit it on the Edit Page, it will Modify:

public ActionResult EditAdmin(User user)
{ 
        persons.Entry(user).State = EntityState.Modified;
        persons.SaveChanges();
}

But the problem is , I have alot of field don't need be modify:

public class User{
    public int UserId {get; set;} // do not need modify
    public int Password {get; set;} // do not need modify
    public string Name {get; set;}
    public bool Sex {get; set;}
    public DateTime AddTime {get; set;} // do not need modify
}

Obviously, I can't display some field on my edit page use Hidden, because I don't want it display on UI. but when submit, I still need it still keep the original value. So Is there any good idea for it? Thanks

Update1:

Why I can't use like

entry.Property(e => e.Password).IsModified = false;

link: https://stackoverflow.com/a/18004476/1900498

But It will display :

Validation failed for one or more entities. See 'EntityValidationErrors' property for more details.