31.—Can you tell me what time the flight to Detroit leaves? —I'm sorry, but it ______.
He made another wonderful discovery, ______ of great importance to science.
When they met again, the two friends talked about lots of things and persons ______.we could remember in the school.
The factory ______ I am going to is the place ______ my mother used to work many years ago.
Who can pwhat life will be like in the future?
---Would you mind if I turned on the TV? ---Not at all. _______