5 exercises — choosing must, should, might, could, and may correctly in debugging, runbooks, and engineering discussions.
0 / 13 completed
1 / 13
A code review comment states: "This __ be a race condition — the logs show two threads accessing the cache simultaneously." Which modal expresses the highest degree of certainty about a present deduction?
"must" expresses near-certainty based on logical deduction. When you have strong evidence and are drawing a firm conclusion, use must: "This must be a race condition", "The memory leak must be in the event listener." The certainty scale for modals of deduction: must (90–99% certain — strong evidence, logical conclusion) → should (70–80% — expected based on design) → might / may / could (30–50% — possible but not confirmed). In code review and debugging, using the right modal signals your confidence level to colleagues. "It must be a race condition" means you have evidence; "it might be a race condition" means you're speculating. Option B ("could") and A ("might") express possibility, not certainty. Option D ("should") implies expected behaviour, not a diagnosis.
2 / 13
A runbook says: "If the pod fails to start, there __ be a misconfiguration in the environment variables." Which modal best expresses a likely but not certain cause?
"may" expresses possibility — the cause is plausible but not confirmed. Runbooks and troubleshooting guides often list possible causes using may or might: "The pod may be failing due to resource limits", "The timeout may indicate a DNS resolution issue." must would imply certainty — incorrect if you're listing possibilities. will expresses future certainty or habitual behaviour. shall is formal and mostly used in legal/contractual contexts (rare in technical docs). In troubleshooting documentation, the progression is: "The pod may fail if X" (possible) → "The pod will fail if X" (certain, documented behaviour) → "The pod must be restarted" (required action).
3 / 13
An architecture decision record (ADR) says: "With connection pooling, query response times __ drop significantly under load." Which modal expresses a confident prediction based on design?
"should" expresses a confident expectation or prediction based on design intent or best practices: "With caching, latency should drop", "With horizontal scaling, throughput should increase." It implies "if things work as designed, this is the expected outcome." must is too strong for a prediction — it expresses obligation or near-certainty about a fact. might and could introduce doubt ("there's a chance it might drop") — appropriate for speculation, not confident predictions. In ADRs and technical proposals, should is the right signal: "This approach should improve performance by 40%." It commits to an expected outcome without making an absolute guarantee.
4 / 13
During a sprint planning discussion, a developer says: "The feature __ be ready by Friday — we're on track, but the API integration is still in progress." Which modal correctly signals cautious optimism?
"should" is perfect for cautious optimism: it signals that the outcome is expected and probable, but acknowledges that conditions must hold. "The feature should be ready by Friday" communicates confidence with a slight hedge — preferable to "will" if there's ongoing work. will expresses certainty ("The feature will be ready by Friday" — you're committing fully, no room for slippage). Using will when things are uncertain sets unrealistic expectations. must expresses obligation or logical deduction, not prediction. shall is archaic in tech contexts. Sprint communication tip: Use should for predictions with mild uncertainty, will only when you're fully confident, and might when the delivery is in doubt.
5 / 13
A ticket comment reads: "The test failure __ be related to the flaky network mock — we've seen this before, but I haven't confirmed it yet." Which modal pair is most appropriate for this level of uncertainty?
"might / could" both express possibility with uncertainty — exactly the right signals when you're speculating without confirmation. "The test failure might be related to the flaky network mock" or "It could be the mock" both signal: "I have a hypothesis, not a conclusion." The difference between the two: might is slightly more tentative than could, but in practice they're interchangeable for possibility. In tickets, Slack threads, and PR comments, calibrating your modals matters: "it must be the mock" implies certainty and can mislead colleagues; "it might be the mock" keeps the investigation open. Best practice: "It could be X — I'll confirm after running the isolated test." This keeps communication honest and prevents premature root-cause assumptions.
6 / 13
git commit -m "Fix: Resolve issue with database connection"
During a code review, Sarah comments: 'This commit must have resolved the connection error.' Which modal verb best reflects her strong belief based on the commit message?
'Must' expresses a high degree of certainty. Sarah is stating that, based on the commit message indicating a fix for a database connection error, she believes definitively that the issue has been resolved. Options 'likely', 'possible', and 'probable' all indicate lower levels of confidence; 'certain' is the most precise reflection of her statement.
7 / 13
git commit -m "Fix: Resolve issue with database connection"
During a code review, Sarah comments: 'This commit must have resolved the connection error.' Which modal verb best reflects her strong belief based on the commit message?
'Must' expresses a high degree of certainty. Sarah is stating that, based on the commit message indicating a fix for a database connection error, she believes definitively that the issue has been resolved. Options 'likely', 'possible', and 'probable' all indicate lower levels of confidence; 'certain' is the most precise reflection of her statement.
8 / 13
git commit -m "Fix: Resolve issue with database connection"
During a code review, Sarah comments: 'This commit must have resolved the connection error.' Which modal verb best reflects her strong belief based on the commit message?
'Must' expresses a high degree of certainty. Sarah is stating that, based on the commit message indicating a fix for a database connection error, she believes definitively that the issue has been resolved. Options 'likely', 'possible', and 'probable' all indicate lower levels of confidence; 'certain' is the most precise reflection of her statement.
9 / 13
Code Review Comment: 'The server response time should be within acceptable limits after deploying this change.' Which modal verb best reflects the reviewer's expectation based on a standard performance metric? Consider the context of monitoring and alerting.
'Could' expresses possibility and reasonable expectation given the context of monitoring. 'Must' implies absolute certainty, which is unlikely in a performance review. 'Might' indicates low probability; 'Will' suggests a definite future outcome that hasn't yet occurred. The reviewer isn't claiming absolute guarantee but expects adherence to a standard.
10 / 13
Slack Message: 'I'm pretty sure the new database schema is causing the slow queries. We need to investigate further before escalating.' Which modal verb best captures the developer's current assessment of the situation? The message suggests a preliminary hypothesis.
'Must' is used for strong conviction or obligation but in this case, it's a subjective belief. 'Will' indicates future certainty; 'Should' suggests advice or expectation and 'Might' expresses possibility. The phrase 'pretty sure' directly indicates the developer's level of confidence – a degree of uncertainty.
11 / 13
PR Description: 'If we implement this caching layer, latency must decrease significantly. The performance tests indicate a positive correlation.' Which modal verb best indicates the developer's confidence in the predicted outcome of the change? This is a key justification for the PR.
'Must' expresses certainty based on evidence. The phrase 'indicate a positive correlation' strengthens this claim, suggesting that the tests provide strong support. 'Could,' 'may', and 'should' all express lower degrees of confidence or possibility; relying on these words would undermine the justification for the PR.
12 / 13
Standup Update: 'We believe the new authentication service will be stable by Monday. We're running some final integration tests.' Which modal best reflects the team's current state of knowledge and their projected timeline? Consider the iterative nature of development.
'Must' is too strong given that it's a projection based on testing. 'Will' implies a definite outcome; 'Should' suggests an expectation and 'Might' indicates possibility. The team's statement reflects their belief based on current progress and tests, acknowledging the inherent uncertainty of final stability.
13 / 13
API Response: 'The API returns a 404. This indicates that the resource does not exist.' Which modal verb best describes the system's response based on the error code? Consider the nature of an API endpoint.
'Must' indicates a definitive consequence – an error code *must* signify that a resource is missing. 'Should' suggests a recommendation; 'Could' expresses possibility and 'Will' implies future certainty. The API response itself communicates the unequivocal nature of the error.
What will I practise in "Modal Verbs for Certainty and Uncertainty — Grammar Exercise"?
Practice modal verbs (must, should, might, could, may) in technical IT contexts: debugging, runbooks, ADRs, and sprint planning. 5 interactive exercises.
How many exercises are in this module?
This module has 13 multiple-choice exercises, each with instant feedback and a full explanation of the correct answer.
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