5 exercises — use must, should, shall, and may precisely in specifications, RFCs, and code reviews, following the RFC 2119 keyword conventions.
0 / 18 completed
1 / 18
An author is writing an RFC and wants to state an absolute requirement, following RFC 2119 conventions. Which sentence is correct?
"MUST" as an absolute requirement: Under RFC 2119, the keyword MUST (and its synonyms REQUIRED and SHALL) signals an absolute, non-negotiable requirement for conformance. Should only expresses a strong recommendation that may be ignored with good reason. Can expresses ability or permission, not obligation, and might expresses mere possibility. For a security control that is mandatory, only must conveys the binding force the specification needs.
2 / 18
In a spec, you want to say a behaviour is recommended but not mandatory. Which modal fits the RFC 2119 keyword "SHOULD"?
"SHOULD" as a recommendation:SHOULD means there may be valid reasons to ignore the item in particular circumstances, but the full implications must be understood and weighed before choosing a different course. Must and shall are too strong (absolute requirements), while could is too weak — it merely notes a possibility and carries no recommendation. Reserve should for best practices that you advise but do not strictly enforce.
3 / 18
A reviewer wants to forbid a behaviour absolutely in a protocol spec. Which negative modal is correct for "MUST NOT"?
"MUST NOT" as an absolute prohibition:MUST NOT (synonym SHALL NOT) is the RFC 2119 keyword for an absolute prohibition. Should not only discourages the behaviour. Need not means the behaviour is optional — the opposite of a prohibition. Cannot describes a technical impossibility rather than a normative rule; here the server is technically able to leak the hash, so we must prohibit it, not claim it is impossible.
4 / 18
An engineer is drawing a logical conclusion from logs in a postmortem. Which modal expresses near-certainty based on evidence?
"Must have" for deduction: When you draw a confident logical conclusion from available evidence, English uses must have + past participle (epistemic must). The logs make the cause almost certain, so must have been caused is correct. Should have implies an expectation that was not met, can have is non-standard in affirmative deductions (use could have for possibility), and will have been refers to a future-perfect prediction, not a deduction about a past event.
5 / 18
A tech lead wants to make a polite, tentative suggestion in a code review comment. Which modal is most appropriate?
"Might want to" for tentative suggestions: In collaborative code reviews, might want to softens a suggestion and respects the author's autonomy, which helps maintain a constructive tone. Must and shall impose an obligation that is too forceful for an optional refactor. Can simply states the action is possible and lacks the recommending nuance. Choosing the right strength of modal is central to professional, diplomatic technical communication.
6 / 18
Code Review Comment: Alex writes the following comment on a PR:
// This function MUST return a valid JSON object.
Which modal verb best expresses the requirement in this context?
The word 'must' is the standard modal verb used in code reviews to denote a firm requirement. Using 'should' or 'could' would be too weak and wouldn't effectively communicate the need for a specific JSON format. The incorrect options present alternative usages of modals that don't fit this context.
7 / 18
Standup Update: Maria is reporting on her progress.
Maria says:
// I will investigate the logging system and determine if it's providing sufficient information.
Which modal verb best expresses Maria's intention?
'Should' indicates an intention or a course of action based on available information. It suggests Maria will investigate and potentially improve the logging system. The other options suggest stronger commitments (must) or more definitive outcomes (ensure, verify).
8 / 18
Code Review Comment: Alex writes the following comment on a PR:
// This function MUST return a valid JSON object.
Which modal verb best expresses the requirement in this context?
The word 'must' is the standard modal verb used in code reviews to denote a firm requirement. Using 'should' or 'could' would be too weak and wouldn't effectively communicate the need for a specific JSON format. The incorrect options present alternative usages of modals that don't fit this context.
9 / 18
Standup Update: Maria is reporting on her progress.
Maria says:
// I will investigate the logging system and determine if it's providing sufficient information.
Which modal verb best expresses Maria's intention?
'Should' indicates an intention or a course of action based on available information. It suggests Maria will investigate and potentially improve the logging system. The other options suggest stronger commitments (must) or more definitive outcomes (ensure, verify).
10 / 18
David, a senior engineer, needs to document a critical API endpoint. He wants to state that all clients *must* authenticate before accessing the data. Which modal verb best suits this requirement?
The word 'must' is the standard modal verb used in technical documentation to denote a strict requirement. Using 'should' or 'could' would weaken the statement and potentially lead to non-compliance. 'Will' implies a future action rather than an immediate obligation.
11 / 18
Sarah is writing a Slack message to her team about a potential issue with the new deployment. She wants to suggest that they investigate further but doesn't want to commit to immediate action. Which modal verb best conveys this?
'Might' is the most appropriate modal verb here because it expresses a tentative possibility. It avoids making a firm commitment while still acknowledging that further investigation is warranted. 'Must' implies urgency, and 'will' suggests a definite plan.
12 / 18
Ben needs to describe the expected behavior of a microservice in a PR comment. He wants to state that the service *should* integrate with the existing authentication system. Which modal verb is most accurate?
'Can' is the correct modal to use when describing expected behavior. It indicates that the service *is able* to integrate with the authentication system, which aligns with common design principles. 'Must' implies a hard constraint, while 'should' suggests recommendation and 'might' introduces uncertainty.
13 / 18
Finn wants to provide feedback on a draft API specification. He believes the documentation *could* benefit from more detailed examples. Which modal verb is most appropriate for this suggestion?
'Should' is the best choice here because it expresses a suggestion or recommendation. It's polite and constructive without imposing a strict requirement. 'Must' would be overly forceful, while 'will' focuses on action rather than improvement, and 'can' describes ability.
14 / 18
Liam is reviewing a PR for a new authentication service. He needs to clearly state that all requests to the endpoint /usersmust include an API key.
Which modal verb best expresses this requirement?
The word must indicates a strict obligation and is appropriate when specifying security requirements. Might, could, and should all express lower levels of certainty or recommendation, which wouldn't be suitable for enforcing authentication protocols. Using must clarifies the absolute necessity.
15 / 18
David is documenting the behavior of a new API endpoint in a PR description. He wants to state that the endpoint /data/v1should return data in JSON format.
Which modal verb best conveys this recommendation?
The word should is used to express a recommendation or suggestion; it indicates what is desirable but not necessarily mandatory. Can implies ability, will suggests commitment, and would expresses hypothetical situations – none of which fit the context of documenting API behavior.
16 / 18
Emily is writing a comment on a code review for a new feature that processes user input. She wants to state that the function could handle various data types.
Which modal verb best suits her intention?
Can indicates possibility and capability – it's appropriate when describing the potential functionality of a function. Using should would be a recommendation, will implies commitment, and must is overly restrictive for this scenario.
17 / 18
Finn needs to describe the expected behavior of a service that updates user profiles. He wants to state that the service must validate all input fields before updating the database.
Which modal verb is most appropriate for this requirement?
The word must indicates a strict obligation and is appropriate when specifying data integrity requirements. Using may, could, or should would imply less stringent control, potentially leading to invalid data being stored in the database. Therefore, must clearly defines the necessary validation.
18 / 18
John, a QA engineer, is testing a new API. He needs to document the expected response format for a successful request. He wants to state that the API *should* return a 200 OK status code with a JSON payload. Which modal verb best suits this description?
'Could' is the most appropriate modal verb here because it conveys a suggestion or recommendation without imposing a strict requirement. The API *might* return a 200 OK, but there could be circumstances where another status code is acceptable. 'Must' would imply an inflexible rule, and 'will' suggests certainty which isn't warranted in this exploratory testing phase.
What will I practise in "Modal Verbs for Technical Communication — Grammar Exercises"?
Practise must, should, shall, and may in specs, RFCs, and code reviews following RFC 2119 keywords. 5 advanced exercises with detailed explanations.
How many exercises are in this module?
This module has 18 multiple-choice exercises, each with instant feedback and a full explanation of the correct answer.
Is this exercise free to use?
Yes. Every exercise on CoderSlingo, including this one, is free to use with no account, sign-up, or paywall.
Do I need to create an account to do these exercises?
No account is required. Just click an option to answer — your score for this session is tracked automatically in the progress bar above.
What happens if I choose the wrong answer?
You'll immediately see which answer was correct, plus a full explanation covering the grammar rule and reasoning behind it — mistakes are where most of the learning happens.
Can I retry the exercises if I want a higher score?
Yes — use the "Try again" button on the results screen to reset and go through all the questions again.
Is my progress saved if I close the page?
No. Progress is tracked only for your current visit; reloading or leaving the page resets the counter. This keeps the exercise simple and account-free.
Where can I find more Grammar exercises?
Browse the full Grammar hub for related drills, or check the "Next up" link below to continue with a connected topic.
How is this different from reading an article on the same topic?
Articles explain grammar rules in prose; this exercise tests and reinforces those rules through active recall with immediate feedback — the two work best together.
Who writes these exercises?
Every exercise is written by the CoderSlingo team, drawing on real workplace English used in IT roles, then reviewed for accuracy and clarity.