Employees may not smoke in this office.
Are both of the following sentences acceptable equivalents of the above sentence?
Employees are not allowed to smoke in this office. Yes.
Employees are not able to smoke in this office. No. The problem with "able to" is that it suggests a physical ability. Anyone is "able to" smoke, if they choose to do so. "May not" is generally accepted to mean a prohibition, nothing to do with ability.
(I know that "can't" can be used instead of "are not able to".)
How about the past tense?
It was forbidden for employees to smoke in this office. Yes.
Employees were not allowed to smoke in that office. Yes.
Employees were not able to smoke in that office. No, same reason.
Thanks in advance to any native speaker for answering these questions!
PS - Great forum!