We arrived at airport. We realized our passports were still at home.
- A. It was until we arrived at the airport that we realize our passports were still at home.
- B. We arrived at the airport and realized that our passports arc still at home.
- C. Not until had we arrived at the airport, we realized our passports were still at home.
- D. Not until we arrived at the airport, did wc realize that our passports were still at home.