Air pollution is getting more and more serious, so we must take action __________ it is too late.
_____ of the students who took part in the military training is 450.
He said, “Don’t do that again.” He _____ me _______ that again.
—Who called just now, Sam? —It’s Terry. She asked _____.
I don’t think it was an accident at all. Your brother did it _____.
—Have you finished your experiment report, Jane? —Oh, my God. I’ve _____ forgotten all about that.