The footprints were 60 cm long. They must/ might / can't be a human step.
CAN'T
The woman is talking about the masks. I’m sure she must / might / can’t be a teacher
MUST
The boys are wearing the same hats. They must / might / can’t be brothers, but I’m not sure.
MIGHT
The girl and the boy are smiling. They might / can’t / must be interested in the masks or they might be telling jokes
MIGHT
I think there must/ might / can't be more than one monster, but I’m not sure
MIGHT
Only a few people have seen it, so it must/ might / can't be under the water most of the time.
MUST
This dinosaur-like monster lives in the lake of Champlain, USA.
CHAMP
That boy looks strange. He must / might / can’t be going to take something from the museum, but I’m not sure
MIGHT
This monster has an eye as big as a human head
GIANT SQUID
The bracelets are gold. They must / might / can’t be expensive
MUST
It's a dog-like creature that lives in Puerta Rico
CHUPACABRA
That tomb looks very old. It must / might / can’t be modern.
CAN'T
This beast lives in a forest, USA. It smelled terrible
BIGFOOT
Whose backpack is that? It might / must / can’t be yours because you’ve got one on your back
CAN'T