Who ______ it be that hasn’t handed it in yesterday. —It _______ be Bob. He handed it in yesterday.

Engines are to machines ________ hearts are to animals

It is reported that the police will soon ______the case of two missing children

Lionel Messi, ______ the record for the most goals in a calendar year, is considered the most talented football player in Europe

We must work hard toa good knowledge of English