—Who______ it be that is knocking at the door? —It ______ be Father, but I’m not sure.
The mother along with her children _______ in the supermarket when the explosion happened.
I wish to thank Professor Smith, without _______help I would never have got this far.
The problem, according to the experts, is _______ we should do with the salty land.
He has always insisted on _______ Mr. Berg instead of Justin.
When Peter speaks in public, he always has difficulty ______ the right things to say.