must be doing

USAGE SUMMARY

The phrase "must be doing" is correct and usable in written English.
It can be used to express a strong assumption or belief about someone's current actions or state. Example: "She must be doing her homework right now since she hasn't answered her phone."

✓ Grammatically correct

News & Media

Science

Human-verified examples from authoritative sources

Exact Expressions

58 human-written examples

You must be doing somersaults!

The New Yorker

They must be doing something right.

The New Yorker

The system must be doing something right.

The New Yorker

I must be doing something right".

The New York Times

You must be doing a video today".

The New York Times

Still, Nissan must be doing something right.

The New York Times

Megu must be doing something right.

The New York Times - Food

We must be doing something right.

The New York Times

"But we must be doing something right".

The New York Times

It must be doing something right.

The New York Times - Sports

They must be doing something useful".

The New Yorker

Expert writing Tips

Best practice

Use "must be doing" to express a logical deduction or strong belief about an ongoing action based on available evidence or context. For instance, "The lights are on; they "must be doing" something inside".

Common error

Avoid using "must be doing" when you only want to express a possibility or weak likelihood. If you're unsure, opt for phrases like "might be doing" or "could be doing" to indicate uncertainty.

Linguistic Context

The phrase "must be doing" functions as an epistemic modal indicating a high degree of certainty about an ongoing action or state. It suggests a logical deduction based on available evidence, as demonstrated by Ludwig examples where it's used to infer current activities.

Expression frequency: Very common

Frequent in

News & Media

84%

Science

8%

Formal & Business

4%

Less common in

Academia

2%

Encyclopedias

1%

Wiki

1%

Ludwig's WRAP-UP

The phrase "must be doing" is a versatile and frequently used construction for expressing strong assumptions about current actions or states. Analysis of real-world examples indicates it's grammatically sound and suitable for a range of contexts, particularly in news and media. As confirmed by Ludwig AI, the phrase effectively conveys a speaker's confidence based on available evidence. To ensure correct usage, remember to reserve it for situations where you have a solid basis for your deduction and opt for alternatives like "might be doing" when expressing uncertainty.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

has to be doing

Indicates a strong obligation or necessity, similar to a logical deduction.

is probably doing

Expresses a high degree of likelihood or probability.

is likely doing

Suggests something is expected or anticipated to be happening.

is bound to be doing

Implies inevitability or certainty about an ongoing action.

is undoubtedly doing

Emphasizes that there is no question about the action taking place.

will certainly be doing

Highlights confidence about a future action that's currently ongoing.

I imagine is doing

Conveys a personal belief or guess about an action.

I expect is doing

Indicates expectation of an action based on past experience.

one can assume is doing

Indicates possibility that someone is doing an action.

may well be doing

Expresses that something is quite possible or likely.

FAQs

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

Use "must be doing" to express a strong assumption or logical deduction about an ongoing action. For example, "She hasn't left her room all day; she "must be doing" something important".

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

"Must be doing" implies a high degree of certainty based on available information, while "might be doing" suggests possibility or uncertainty. "He "must be doing" well if he bought a new car" (strong assumption) versus "He "might be doing" well, but I'm not sure" (uncertain).

What are some alternatives to "must be doing"?

Depending on the context, you can use phrases like "has to be doing", "is probably doing", or "is likely doing" as alternatives to "must be doing".

Is "must be doing" formal or informal?

The phrase "must be doing" is appropriate for both formal and informal contexts, as it's grammatically correct and widely understood. However, in very formal writing, you might opt for alternatives like "is undoubtedly engaged in" for added sophistication.