--- Is this ______ apple? ---- No, it’s ______ orange.
You ________ wait for him. I’m not sure whether he’ll come back or not today.
—Why do you look so tired?—Because we ________ for three hours without stopping.
We won’t start the meeting ________ the teacher arrives.
The workers are trying to ________ what’s wrong with the machine.
Internet is ________ used by people, especially by young people.