that must be

USAGE SUMMARY

The phrase "that must be" is correct and usable in written English.
You can use it to express that you believe something is true, based on the evidence you have. For example, "He said he had been to Paris last week; that must be why he was so excited."

✓ Grammatically correct

News & Media

Science

Wiki

Human-verified examples from authoritative sources

Exact Expressions

60 human-written examples

Yes, that must be earned.

Independent

"Oh, that must be so interesting.

The New Yorker

These are values that must be taught.

The New York Times

that must be considered?

The New York Times

It something that must be done.

SEP

Refrigerate items that must be stored cold.

WikiHow

Family matters that must be attended to.

WikiHow

This is something that must be avoided.

EU Parlament

That must be hard.

Independent

That must be fixed.

The New York Times

That must be good.

The Economist

Expert writing Tips

Best practice

"That must be" is often followed by an adjective, noun phrase, or adverbial clause to specify what "that" refers to. Ensure that the pronoun 'that' has a clear and unmistakable antecedent.

Common error

While "that must be" is perfectly acceptable, overusing it can make your writing sound less sophisticated. In formal contexts, consider more precise alternatives such as "it is likely that", "it can be inferred that", or "evidence suggests that".

Linguistic Context

The phrase "that must be" functions as an epistemic modal, expressing a degree of certainty or logical inference based on available information. Ludwig AI validates this usage, and examples show it drawing conclusions from observed facts or statements.

Expression frequency: Common

Frequent in

News & Media

45%

Science

30%

Wiki

15%

Less common in

Formal & Business

5%

Encyclopedias

3%

Reference

2%

Ludwig's WRAP-UP

In summary, the phrase "that must be" is a common and grammatically sound way to express a logical conclusion or inference. As Ludwig AI confirms, it's used across various contexts, primarily in news, scientific writing, and informal communication. While perfectly acceptable, overuse in formal writing may benefit from more precise alternatives. Remember to ensure the pronoun "that" has a clear antecedent. Considering that it functions as an epistemic modal, it's best to use it when the evidence strongly suggests a particular conclusion. By following these guidelines, you can effectively use "that must be" in your writing.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

it has to be

Focuses on obligation or necessity, rather than a deduction based on evidence.

it must surely be

Adds emphasis to the speaker's certainty.

it is likely to be

Presents a possibility with a degree of probability.

it seems to be

Indicates an appearance or impression, rather than a definitive conclusion.

it would have to be

Suggests inevitability or a lack of alternative options.

it's bound to be

Implies a strong expectation based on past experiences or patterns.

that appears to be

Emphasizes the visual or observable evidence.

that seems like it would be

Introduces a hypothetical element or consideration.

it's quite possibly

Reduces the level of certainty, suggesting a possibility rather than a strong belief.

i daresay it is

An old-fashioned expression suggesting a tentative agreement or assumption.

FAQs

How can I use "that must be" in a sentence?

"That must be" is used to express a conclusion or inference based on available evidence. For instance, "The lights are off; "that must be" because nobody is home."

What are some alternatives to "that must be"?

Depending on the context, you can use alternatives such as "it has to be", "it seems to be", or "it is likely that".

Is it correct to say "that must have been" instead of "that must be"?

Yes, "that must have been" is correct when referring to something in the past. For example, "He arrived late; "that must have been" due to traffic."

What's the difference between "that must be" and "that might be"?

"That must be" indicates a stronger belief or conclusion, while "that might be" suggests a possibility or uncertainty. "That must be" implies more confidence based on the available information.