they must not

USAGE SUMMARY

The phrase "they must not" is correct and usable in written English.
It can be used to express a prohibition or something that is not allowed. Example: "In this experiment, they must not touch any of the equipment without permission."

✓ Grammatically correct

News & Media

Human-verified examples from authoritative sources

Exact Expressions

56 human-written examples

They must not keep silent".

Independent

They must not waste it.

The Economist

They must not think shortsightedly.

The New York Times

They must not fight alone.

The New York Times

They must not be taken for granted.

The New York Times

But they must not be too severe.

The Economist

They must not be real swords.

The New Yorker

They must not be allowed to vote.

The New York Times

They must not succeed," he said.

The Economist

"They must not think shortsightedly," they add.

The New York Times

They must not develop nuclear capability.

The New York Times

Expert writing Tips

Best practice

Use "they must not" to express a strong prohibition or requirement, particularly when outlining rules or guidelines. For instance, "Participants in the study they must not share the confidential data with external parties."

Common error

Avoid using "they must not" when you intend to offer a suggestion or recommendation. Instead, use "they should not" or "it's best if they don't" to convey a less forceful tone. For example, instead of saying "They must not skip steps in the process," consider saying "They "should not" skip steps in the process" for a softer approach.

Linguistic Context

The phrase "they must not" functions as a prohibitive expression. It combines the third-person plural pronoun "they" with the modal verb "must" (indicating obligation) and the negation "not", creating a strong directive against a particular action. Ludwig AI validates its usage in contexts requiring clear and firm restrictions.

Expression frequency: Very common

Frequent in

News & Media

96%

Science

2%

Formal & Business

2%

Less common in

Encyclopedias

0%

Wiki

0%

Reference

0%

Ludwig's WRAP-UP

The phrase "they must not" is a highly common and grammatically correct way to express a strong prohibition or requirement, as confirmed by Ludwig AI. Primarily found in news and media contexts, it conveys a neutral to formal tone, indicating that certain actions are strictly forbidden. Alternative phrases include "they "should not"" and "they "cannot"", offering varying degrees of emphasis. When using "they must not", ensure it aligns with the intended tone and that a less forceful alternative is employed when offering mere suggestions. Ludwig's examples illustrate diverse scenarios where this phrase effectively communicates necessary restrictions and guidelines.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

they should not

Replaces "must" with "should", indicating a recommendation rather than a strict requirement.

they cannot

Indicates an impossibility or lack of permission, rather than a prohibition.

they are not allowed to

Explicitly states that permission is withheld, often in a formal context.

it is imperative that they don't

Emphasizes the importance of avoiding a particular action or outcome.

they are forbidden to

A more formal way to express prohibition, suggesting a rule or law is in place.

under no circumstances should they

A stronger, more emphatic way to express that something is not allowed.

they are prohibited from

Formally prohibits an action, often used in legal or official contexts.

they are advised against

Indicates a strong recommendation not to do something, often based on potential negative consequences.

they ought not to

Suggests a moral or ethical reason for avoiding an action.

they better not

A more informal and forceful way of saying something should not happen, often implying a threat.

FAQs

How can I rephrase "they must not" to sound less formal?

For less formal situations, you can use phrases like "they "should not"", "they "better not"", or "they "are not supposed to"", depending on the context and the level of emphasis you want to convey.

Is there a stronger way to express "they must not"?

Yes, you can use phrases such as "they "cannot"", "they are strictly prohibited from", or "under no circumstances should they" to convey a stronger sense of prohibition.

What's the difference between "they must not" and "they should not"?

"They must not" indicates a strict prohibition or requirement, whereas "they "should not"" suggests a recommendation or advice. The former implies a consequence for non-compliance, while the latter is a gentler suggestion.

In what situations is it appropriate to use "they must not"?

"They must not" is appropriate in contexts where rules, regulations, or serious consequences are involved. Examples include safety instructions, legal documents, or when giving critical advice where non-compliance is unacceptable.