2 added 28 characters in body
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All of the could'could' uses here are equal meaning that 'it's a possibility'

If I substituted it for may'may' or might'might' we would then start talking about the probability of it happening, since it was affirmed that he wouldn't do the action, the use of 'may'may' or might''might' would be very inappropriate here.

All of the could uses here are equal meaning that 'it's a possibility'

If I substituted it for may or might we would then start talking about the probability of it happening, since it was affirmed that he wouldn't do the action, the use of 'may or might' would be very inappropriate here.

All of the 'could' uses here are equal meaning that 'it's a possibility'

If I substituted it for 'may' or 'might' we would then start talking about the probability of it happening, since it was affirmed that he wouldn't do the action, the use of 'may' or 'might' would be very inappropriate here.

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source | link

All of the could uses here are equal meaning that 'it's a possibility'

If I substituted it for may or might we would then start talking about the probability of it happening, since it was affirmed that he wouldn't do the action, the use of 'may or might' would be very inappropriate here.