Recently I`ve been revising my knowledge about the verb could. I know that could is used as the past form of can to describe a general ability in the past. E.g.
I could work 10 hours a day when I was younger.
For specific situations in the past "to be able to" is preffered, though. E.g.
I was able to get out of the car before it exploded.
Yet, there is another aspect of the modal verb could that got me puzzled, and that is could as the verb used to express permission in the past. I know it is fine to use the expression "to be allowed to" in that context. E.g.
Children were allowed to use calculators during the test.
My question is: Can I use could for expressing both: a general past permission and a specific past permission? For example:
Children could use their mobile phones only during breaks, not during lessons.
Even though I was on the train, I could smoke.