—Who______ it be that is knocking at the door? —It ______ be Father, but I’m not sure.
It’s _______ you do today that will make a difference in your life tomorrow.
Mr Green showed his students some photos ________ at World Expo 2010 Shanghai.
A group of children are looking into the box, ________ about what can be inside.
I must be off now. My friends ________ outside.
David is a great teammate. He knows well how to work with ________.