1. The light in the sky was lightning. (could)
The light in the sky could have been lightning
2. That strange noise woke up the baby. (must)
That strange noise must have woken up the baby
3. Lori didn’t forget Joe’s name. (couldn’t)
Lori couldn't have forgotten Joe's name.
4. We saw more than 100 hoodoos. (may)
We may have seen more than 100 hoodoos.
5. The ending to that story didn’t surprise anyone. (might not)
The ending to that story might not have surprised anyone.
6. People didn’t live in those pyramids. (must not)
People must not have lived in those pyramids.
7. The volcano made that sound. (might)
The volcano might have made that sound
8. They didn’t understand the scientific explanation. (may not)
They may not have understood the scientific explanation.
