/ http://www.slideshare.net/images/logo.gif / 際際滷Share feed for 際際滷shows by User: RogerPak https://cdn.slidesharecdn.com/profile-photo-RogerPak-48x48.jpg?cb=1523164595 As we know, There are known knowns. There are things we know we know. We also know There are known unknowns. That is to say We know there are some things We do not know. But there are also unknown unknowns, The ones we don't know -Rumsfeld