Circle the answer that correctly completes each sentence.
1. The Incas didn’t have any sophisticated machines or work animals. The temples ( must / couldn’t / may ) have been built exclusively by human hands.
2. Dinosaurs may not have died off gradually as the result of climate change. They ( had to / could / would ) have been killed off quickly by some sudden event.
3. I don’t believe in any of those other crazy theories. Stonehenge ( might have been / were / had to have been ) built by ancient Britons many years ago.
4. The Nazca lines are incredible, but I’m certain they weren’t created by people who lived 1,500 years ago. The ancient people ( couldn’t have / would have / must have ) had the knowledge to create something so accurate.
5. Conspiracy fans continue to consider the story of Roswell aliens. They believe that UFOs ( might / couldn’t / had to ) have crashed in the desert.
6. The Mary Celeste ( might have been / had to have been / had been ) attacked by pirates. No one knows for sure.
7. It’s obvious that something terrible happened. The crew ( had to have / would have / might ) abandoned the ship during the incident. There’s no other explanation.
Circle the answer that correctly completes each sentence.
1. The Incas didn’t have any sophisticated machines or work animals. The temples must have been built exclusively by human hands.
2. Dinosaurs may not have died off gradually as the result of climate change. They could have been killed off quickly by some sudden event.
3. I don’t believe in any of those other crazy theories. Stonehenge might have been built by ancient Britons many years ago.
4. The Nazca lines are incredible, but I’m certain they weren’t created by people who lived 1,500 years ago. The ancient people couldn’t have had the knowledge to create something so accurate.
5. Conspiracy fans continue to consider the story of Roswell aliens. They believe that UFOs ( might have crashed in the desert.
6. The Mary Celeste might have been attacked by pirates. No one knows for sure.
7. It’s obvious that something terrible happened. The crew had to have abandoned the ship during the incident. There’s no other explanation.