31. Nobody believed his reason for being absent from the class ______ he had to meet his uncle at the airport.
I think this is the very work that we must finish ____ her.
The work he devoted his time to _____ worth praising.
The theory he sticks to ______ to be of no use in our studies.
The man you referred to _____ just now.
——You didn’t wait for Mr. Black last night, did you? ——No, but we ____. He didn’t return home at all.