.—Who______ it be that is knocking at the door? —It ______ be Father, but I’m not sure.
—— Do you know Jim quarreled with his brother? I don't know, and ______ .
Not once _____ their plan.
His uncle is a worker and has been working in the factory for more than ten years. _____.
Not only _____ a promise, but also he kept it.
_____ and caught the mouse.