—Who______ it be that is knocking at the door?—It ______ be Father, but I’m not sure.
He advised me to read an artile ___ reading ___ an American writer ___ senior Book 3.
Who is ___ the school?
The PLA man made a dive ___ the smoking box.
The naughty boy could hardly tell me the reason ___ being absent ___ school.
He had a hard time ___ supporting the family.