1. They needn't have sent the letter. - Did they send the letter?

2. Simon did not need to charge the battery. - Did Simon charge the battery?

3. The mist may have disoriented the hikers. - Were the hikers disoriented by the mist?

4. Brian should have kept his mouth shut. - Did Brian keep his mouth shut?

5. Linda oughtn't to have concealed the truth. - Did Linda conceal the truth?

6. Their neighbour should not have left the lights on. - Did their neighbour leave the lights on?

7. They may not have understood the instructions. - Did they understand the instructions?

8. The police needn't have looked into the case. - Did the police look into the case?

9. Julia did not need to comb her hair. - Did Julia comb her hair?

10. The thieves may have taken my bike. - Did the thieves take my bike?