Fill in the blank with must have been, can't (couldn't) have been, have to/had to (be) and didn't have to (be): 1. He knows a lot about flying plane. He _______ a pilot when he was young. 2. Vera _______ at the supermarket this morning. I didn't see her there. 3. John _______ at the bank until 10, so he arrived here five minutes ago. 4. When she _______ at the hospital? Early this morning. 5. We had enough foreign currency left at the end of the holiday, so I _______ buy any more. 6. Monica knew exactly what to do. I _______ tell he twice. 7. There _______ an accident on South Street because the road is closed off. 8. I left a message on your answer phone last night. You _______ out. 9. You _______ waiting long. After all, I'm only five minutes late. 10. The fire alarm went and we _______ out of the building in to minutes.