/ http://www.slideshare.net/images/logo.gif / 際際滷Share feed for 際際滷shows by User: mrolix https://cdn.slidesharecdn.com/profile-photo-mrolix-48x48.jpg?cb=1523556247 Practical: It doesn't matter if the glass is half-full or half-empty, the only thing that matters it that 50% of its volume has been used and you're left with 50% to work with.