—He looks very happy. He ____have passed the exam,
—I guess so. It’s not difficult after all

1. A.
   should
2. B.
   could
3. C.
   must
4. D.
   might

—He looks very happy. He ____have passed the exam,

   —I guess so. It's not difficult after all.

    A. should         B. could              C. must               D. might