must not | mustn’t

The term “mustn’t” is a contraction of “must not”. It is used to indicate that something is prohibited or not allowed, or to suggest that it is a bad or unacceptable idea.

Here are the most common phrases in PlayPhrase.me:

We mustn’t (99)

Strict instructions from Edward,

 we mustn’t be late for his parade.

listen

In this context, it means that it is very important or necessary not to be late for Edward’s parade. It implies that there could be negative consequences if they are late. It’s a way of emphasizing the importance of punctuality in this situation.

I mustn’t (66)
You mustn’t be (37)
But you mustn’t (34)
No you mustn’t (28)
You mustn’t let (24)

The main thing is,

 you mustn’t let him know

 you‘re back yet.

listen to the pronunciation

mustn’t think (23)
mustn’t say (22)
You mustn’t do (21)

Here are our completed examples by AI:

1. We mustn’t forget the importance of kindness in our daily interactions.
2. I mustn’t let my fears stop me from pursuing my dreams.
3. You mustn’t be too hard on yourself, everyone makes mistakes.
4. But you mustn’t let these setbacks discourage you.
5. No, you mustn’t give up on your goals.
6. You mustn’t let negative thoughts control your mind.
7. One mustn’t think that failure is the end, it’s just a stepping stone to success.
8. People mustn’t say things in anger that they may regret later.
9. You mustn’t do anything that goes against your values.

In the English Grammar Profile, the negative form of ‘must’ in the category of MODALITY appears at two levels.

Point 21 is A2 and just general form.

Point 149 is B2 and is defined:

USE: RULES

negative forms of ‘must’ to talk about what is not permitted.

*It is not clear what type of usage the A2 level uses.  If we look at the 2 EGP examples:

You mustn’t forget to buy …
You must not wear a … (rule!)

We can surmise A2 can use basic subjects and verbs with the structure only.  Therefore, B2 should refer to a range of subjects or verbs. For example:

Mr. Iannazzo placed an order at the Robeks and stressed to the staff that the product must not contain peanuts.

context

However, this overlaps B2 Negation with emphasis.

Here are the search results in iWeb corpus for the most common lexical verbs:

must _x _vvi
1 MUST NOT EXCEED 5621 (C1)
2 MUST NOT USE 3904
3 MUST NOT FORGET 3055 
4 MUST NOT CONTAIN 2274 B1

collocate search in COCA

1 ANY 12
2 SUBMISSION 7
3 CHARACTERS 7
4 MATERIAL 7
5 THAN 7

5 MUST NOT ALLOW 1747 (c1)

There’s a very strong feeling in the party, mustn’t allow ourselves to be bullied.

listen

6 MUST NOT LET 1395 (B2 phrasal verb object)

  Jakarta Post

France must not drop guard against COVID-19, minister says – The Jakarta Post

“We must not let down our guard,” Health Minister Olivier Veran told LCI television. “We do not want to resort to another lockdown, we are …

7 MUST NOT TAKE 1320
8 MUST NOT MAKE 1173

9 MUST NOT INCLUDE 1035

  The Independent

Safety experts warn that US trade deal must not include dangerous American cars. Trade Secretary urged to exclude US cars. Jon Stone Policy …

10 MUST NOT GO 950
11 MUST NOT LOSE 846
12 MUST NOT GIVE 804
13 MUST NOT THINK 719
14 MUST NOT BECOME 685
15 MUST NOT GET 606
16 MUST NOT LEAVE 602

17 MUSTN’T FORGET 570

  Burnley Express

Jane Clare of One Foot in the Grapes reaches the letter “I” in her wine alphabet

We mustn’t forget the impact Italy has had on the sparkling wine world with prosecco (but please let’s also give a huge nod to Lambrusco, …

18 MUST NOT CHANGE 551
19 MUST NOT INTERFERE 531 (B2)

Here’s an example of a sarcastic rule.

Millions of young men are going to die and it mustn’t interfere with the cream of broccoli.

listen

20 MUST NOT ATTEMPT 487

Here’s a TED example:

As we find pathways forward for these individuals,

 we must not separate families, we must preserve them.