从方框中选用合适的动词并用其适当时态填空。 quarrel clean hold find fly 1. David is a polite student. He never ____________ with others. 2. —Where is Jack? —He ____________ the floor in the classroom. 3. — ____________ the police ____________ out who stole the money? —No, not yet. But they are busy doing it. 4. We ____________ a party to celebrate Christmas next Sunday, shan't we? 5. His uncle often ____________ to Beijing in the past.