The light is still on. They ___ to turn it off when they left the room.
He came all the way to China for learning it better _______ for making money.
Evidence gained from observation and experiment is often used to _______ a scientific theory.
_______ be sent to work there?
—That must have been a long trip. —Yeah, it _____ us a whole week to get there.
Between the two parts of the concert is an interval, _____ the audience can buy ice-cream.