By Conditionals, Present continuous

When we talk about a subjunctive construction, I think it is easier to understand it without the 'inserted clause, I would think' becasue that way one can clearly see the cause-and-effect relationship beteween the conditional clause and the main clasue. 1. If someone tells you that you may...

1) Do May / Might NOT (like CANNOT) express an interdiction = must not ? ex: ? CJ

Thank you very much, CJ, for your answers! Some more questions if you wouldn't mind: 1) Do May / Might NOT (like CANNOT) express an interdiction = must not ? ex: ? 2) Mrs James is in hospital and HASN’T BEEN ALLOWED TO have (and NOT “could have”) a cigarette after her meals. (correct ?) 3)...