input: Text:... and it comes out here By LESTER DEL REY Illustrated by DON SIBLEY There is one fact no sane man can quarrel with... everything has a beginning and an end. But some men aren't sane; thus it isn't always so! No, you're wrong. I'm not your father's ghost, even if I do look a bit like him. But it's a longish story, and you might as well let me in. You will, you know, so why quibble about it? At least, you always have... or do... or will. I don't know, verbs get all mixed up. We don't have the right attitude toward tenses for a situation like this. Anyhow, you'll let me in. I did, so you will. Thanks. You think you're crazy, of course, but you'll find out you aren't. It's just that things are a bit confused. And don't look at the machine out there too long—until you get used to it, you'll find it's hard on the eyes, trying to follow where the vanes go. You'll get used to it, of course, but it will take about thirty years. You're wondering whether to give me a drink, as I remember it. Why not? And naturally, since we have the same tastes, you can make the same for me as you're having. Of course we have the same tastes—we're the same person. I'm you thirty years from now, or you're me. I remember just how you feel; I felt the same way when he—that is, of course, I or we—came back to tell me about it, thirty years ago. Here, have one of these. You'll get to like them in a couple more years. And you can look at the revenue stamp date, if you still doubt my story. You'll believe it eventually, though,
  Question: What don't they know about the time machine?
  
   (A) who invented it
   (B) what the third set of buttons do
   (C) where it gets stored when not in use
   (D) how to make it go back and forth in time
  Answer:
output: who invented it