—Who______ it be that is knocking at the door? —It ______ be Father, but I’m not sure.
It was in the lab ______ was taken charge of by Professor Harris _______ they did the experiment.
This nice magazine _____ your brother.
The restaurant is _________my uncle.
Can you believe that in ____ a rich country there should be ___many people.
---The window is dirty.----I know. It ______ for weeks.