48. Frank’s wallet is lying on the coffee table. He ______ it here last night.       A. had to leave                 B. will have left            C. must leave                D. must have left 49. We ______ walk all the way home. We ______ take a taxi.       A. could not / had to                                              B. needn’t / can       C. would rather not / must                                     D. ought not to / might 50. I was reading the book last night before I went to bed. I never took it out of this room. It ______ around here somewhere. Where ______ it be?       A. should have been / shall                                    B. could lie / must       C. must be lying / can                                            D. had to be lying / will