GEI-2 UNIT 3 GRAMMAR

The lights in the sky were too bright to be from regular airplanes. They ____ been caused by something unusual.

• may have

• must have

• couldn't have

• can't have

The villagers noticed strange footprints near the forest. They ____ belonged to an animal because they were too large.

• must have

• can't have

• may have

• couldn't have

Some villagers think the lights ____ been a natural phenomenon, but others believe it was supernatural.

• couldn't have

• must have

• may have

• can't have

The explorers didn't return for days. They ____ gotten lost in the dense forest.

• must have

• can't have

• may have

• couldn't have

The loud noise during the lights' disappearance ____ been caused by thunder because the sky was clear.

• can't have

• must have

• may have

• couldn't have

The villagers avoided the forest because they thought the lights ____ been a warning of danger.

• couldn't have

• may have

• must have

• can't have

The missing villagers returned with no memory of what happened. They ____ experienced something traumatic.

• can't have

• may have

• must have

• couldn't have

The lights vanished suddenly and left no trace. They ____ been caused by a machine, as no debris was found.

• can't have

• must have

• may have

• couldn't have

Some villagers believed the lights were a sign from the spirits. It ____ been just a coincidence that the crops failed afterward.

• must have

• couldn't have

• may have

• can't have

Scientists visited the village but found no scientific explanation. They ____ overlooked some critical evidence.

• may have

• must have

• can't have

• couldn't have