—Who______ it be that is knocking at the door? —It ______ be Father, but I’m not sure.
He is a man who is difficult ____.
---Where is my new football shoes, Mum? I need them to play football with my friends. ---I haven’t seen them. You ____ somewhere in your room.
Is this the computer you want to _____?
The young man went into the cinema and after ____ seemed half an hour he came out.
The environmental problem we are looking forward to _____ is __________ our attention.