Course book: Unit20

10: 1.c
       2. e
       3.d
       4.b
       5.a
11: 1. Must
       2. may/might
       3.can’t
       4. may/might
       5.can’t
12: 1.d
       2.e
       3. g
       4.f
       5. a
       6.b
       7.c
14: 1. She must be coming back.
       2. He may lost his way.
       3.He can’t have failed his exams.
      4.She could have forget the appointment.
      5.She can’t have committed the crime.
      6. She might lied to you.
      7.She must be till working in her office.
      8.They could have been sleeping when you called them.
      9. He can’t have paid the rent.