— ____can we board our plane? — In twenty minutes.A. How soon B. How long C. How often
—Can I go to the park, Mum? —Certainly. But you ______ be back by six o’clock.
—I’m leaving now. —______ you turn off the lights and the computer.
The population problem may be ______ one of the world today.
Don’t ______ so often. It’s bad for your health.
—Mum, when can I watch TV? —As soon as your homework ______.