单选题 My pain ______ obvious the moment I walked into the room, for the first man I met asked me pitifully, "Are you feeling all right?"
  • A. must be
  • B. could be
  • C. must have been
  • D. could have been


【正确答案】 C
【答案解析】must have done表示对过去发生事情的肯定猜测，意为“肯定……；一定”。