“Mustn’t” is a contraction of “must not”, used to indicate prohibition or to suggest that something is a bad or unacceptable idea. It’s frequently used in phrases like “We mustn’t” (99 instances), “I mustn’t” (66 instances), “You mustn’t be” (37 instances), and so on.
In the sentence “Strict instructions from Edward, we mustn’t be late for his parade”, it emphasizes the importance of not being late for Edward’s parade. Other examples include “I mustn’t let my fears stop me from pursuing my dreams” and “You mustn’t be too hard on yourself, everyone makes mistakes”.
In English grammar, the negative form of ‘must’ appears at two levels. At A2 level, it’s used with basic subjects and verbs, while at B2 level, it’s used to talk about what is not permitted with a range of subjects or verbs. For instance, “Mr. Iannazzo placed an order at the Robeks and stressed to the staff that the product must not contain peanuts.”
The most common lexical verbs used with “must not” in the iWeb corpus include “exceed”, “use”, “forget”, and “contain”. For example, “France must not drop guard against COVID-19, minister says – The Jakarta Post” and “Safety experts warn that US trade deal must not include dangerous American cars. Trade Secretary urged to exclude US cars. Jon Stone Policy …”.
