He used to ______ cards, but now he is used to _______ a walk after supper.
No one but the experts in this field can _____ the difference between them.
—Who______ it be that is knocking at the door? —It ______ be Father, but I’m not sure.
The meeting we had ________ to _______ us finally.
The great _____ of this computer is that it’s so cheap compared to the others.
The difficulty we now meet with is ___________ we can persuade him to tell the truth.