could and might to talk about future possibility

I have problem with using could in the future possibilities

for example:

They have the technology, but unless the government makes stricter laws, car companies ____ do it.

With which one should I fill the blank of….. Might not or Couldn’t and why ?

Thank you 🙂


‘Could’ discusses fundamental possibility; whether or not the thing can be done.

‘Might’ discusses likelihood of the thing happening; whether or not the thing will be done.

‘Could’ discusses can and can’t.

‘Might’ discusses will, might, and won’t.

In your example it wouldn’t be fundamentally impossible for the car companies to do the thing, but without sufficient incentive they might not do the thing.

Use might not or, if you’re willing to speculate on the nature of car companies, use won’t.

Source : Link , Question Author : Flash , Answer Author : Dave Magner

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