Nado, 'mustn't' isn't used very often in the US. 'Can't' is used more often than 'mustn't'.can't if the speaker is a friend.
mustn't if the speaker is a official.
Nado, 'mustn't' isn't used very often in the US. 'Can't' is used more often than 'mustn't'.
See Changing the mood of a sentence (modals) - english-at-home.com for clarification.
You are absolutely correct, Barb! (I just can't bring myself to say mustn't! The silent 't' drives me crazy!) ;-)Isn't mustn't more of a moral imperative? You mustn't say such things! You mustn't go to a dinner party without a hostess gift. You mustn't touch this cake before our guests come over.
While can't is an impossibility? You simply are unable to do it.