151 Unsolved Mysteries

Unsolved Mysteries


Subject + Modal Verb + Have + Past Participle Verb (V3)

It must have been…

We can use this structure to speculate (guess) about things that happened in the past.

Loch Ness Monster
Loch Ness Monster
Magura Cave Paintings
Magura Cave Paintings

Stonehenge must have been used as a calendar.

Bigfoot could have been a man in a costume.

The Lock Ness monster might have already died!

The cave paintings may have been made to express art.


  • To speculate (6:56) – To guess, assume
  • Sceptical (12:59) – Being unsure about whether something is true, doubting
  • Shrouded (14:40) – Covered by, hidden (a mountain shrouded in fog)
  • Mural (19:55) – A painting on a wall

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