World History Past modals of possibility and probability discussion questions


must/ might/ may/ could + have + past participle to discuss likely and unlikely explanations for historical events

By: Alex Case
Level: Advanced
Topic: General
Grammar Topic: Modals

World history past modals of possibility and probability discussion

Choose one of the conspiracy theories below and change the sentence with words and expressions in the useful language box below to make it have the amount of likelihood that you think is really so. Does your partner agree with you?

Useful language for talking about possibility and probability

“… almost certainly…”

“… almost certainly not…”

“… can’t have…”

“… could have…”                                                                      

“… may have…”

“… must have…”                                                                         

“… might have…”

“… possibly…”                                                                              

“… probably…”


Useful language for agreeing and disagreeing about possibility and probability

“That’s exactly what I think”

“I’d go further and say that…”

“I wouldn’t go that far. I’d say that…”

“I have the opposite point of view. I’d say that…”

Compare some ideas as a class.

Put the language above in order by the level of probability.

100% chance












0% chance


Which ideas below are included in movies, books or TV programmes you know or know about?

What other historical movies have you seen (from your country or other countries)? How likely do you think it is that the story in those movies are true?


Conspiracy theories to discuss the probability of

President Kennedy (=JFK) was assassinated by the CIA in conjunction with the Mafia.


An alien was dissected at the Roswell American air force base.


Jack the Ripper was never caught because he was someone important and the police protected him


The Americans never would’ve used the atom bomb on a European country


The Americans dropped the atom bomb more to scare the Soviet Union than to stop the war, because they knew that the war was going to finish soon anyway


Alexander the Great was gay


9/11 was planned by the US government as an excuse to invade Iraq and so gain control of its oil


There weren’t any Jews in the World Trade Center on 9/11


The explosion in the Pentagon on 9/11 came from inside the building


Princess Diana was murdered by the British Royal Family because she was going to marry a Muslim


The Apollo moon landing was a hoax filmed in a studio by Stanley Kubrick


The Europeans or Americans would’ve got involved in the Yugoslav War earlier if the Bosnians had been Christians


King Arthur was a real person and was a Roman fighting with Ancient Britons against the invading Germanic Anglo Saxons


Mary Queen of Scots was conspiring to assassinate Queen Elizabeth I


The Japanese deliberately delayed the declaration of war until after the attack on Pearl Harbor


Jesus married Mary Magdalene and had a child or children


The main reason British sailors went exploring in the age of Elizabeth I was to impress her and so marry her and become King


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