1. The CEO __ announced the company's new strategy. 2. I don’t need any help; I can do it ___. 3. The teacher ___ checked all the exam papers to ensure fairness. 4. They decorated the hall ___ for the party. 5. The machine started working by __. 6. She designed her wedding dress __. 7. We built this treehouse __ without professional help. 8. The mayor __ attended the ceremony. 9. You should see for __ how beautiful the place is. 10. The scientist __ conducted the experiment to