5 exercises — practise should have, could have, might have, and must have in postmortems and retrospectives.
0 / 5 completed
1 / 5
A postmortem reviewing a missed alert reads: "The on-call engineer _____ the anomaly earlier, but the dashboard was misconfigured." Choose the correct modal perfect form expressing a missed opportunity.
"Should have noticed" is the correct modal perfect form: modal verb + "have" + past participle, used to criticize or express regret about something that did not happen in the past but was expected to. Option A ("should notice") uses the bare present form, which does not express past time. Option C ("should noticed") omits the required auxiliary "have" — modal perfects always need "have" between the modal and the past participle. Option D ("should had noticed") incorrectly uses "had" instead of "have"; the auxiliary after a modal verb is always the base form "have", never "had", regardless of how far in the past the event occurred.
2 / 5
Which sentence correctly expresses a hypothetical past possibility using "could have"?
"Could have been prevented" is correct: "could have" + past participle expresses an unrealized possibility in the past — the circuit breaker was not in place, so the outage was not prevented, but it hypothetically could have been. Option A uses the present modal "could be", which incorrectly shifts the speculation to present or future time, losing the "this was possible but did not happen" meaning. Option B omits "been" and uses the bare form "prevent" instead of the past participle "prevented", which is ungrammatical after "have" in a passive modal perfect. Option D incorrectly uses the gerund "having" instead of the base form "have" after the modal "could".
3 / 5
In a retrospective, an engineer speculates about an uncertain past cause: "The memory leak _____ by the unclosed database connections, though we never confirmed it." Choose the correct modal perfect for a tentative guess.
"Must have been caused" correctly combines the deductive modal "must" (expressing a confident guess) with the passive modal perfect "have been caused" (since the leak was caused by something, i.e., it is the object of causation). Option A ("must be caused") shifts to present tense, which contradicts the past-tense context of the retrospective. Option B ("must have caused") reverses the logic — it would mean the leak itself caused something else, not that the leak was caused by the connections. Option C ("must has been caused") incorrectly uses "has" instead of "have" after the modal, which is always ungrammatical — modals are always followed by the base form.
4 / 5
Which sentence correctly uses "might have" to express an uncertain past possibility about a code review oversight?
"Might have missed" is correct: modal + "have" + past participle. Option A omits "have" entirely, which is ungrammatical. Option B uses "might of", a common written error that results from the way "have" is pronounced as a weak, unstressed syllable in speech (sounding like "of") — this is never correct in writing, technical or otherwise, and should be flagged in any professional document. Option C uses the bare form "miss" instead of the past participle "missed" after "have", which is ungrammatical. This construction is common in code review retrospectives when discussing what plausibly happened without direct evidence.
5 / 5
A postmortem contrasts what actually happened with what was expected: "We _____ deployed on Friday — in hindsight, that was a bad call." Choose the modal perfect that best expresses regret about a decision that was made.
"Shouldn't have deployed" correctly expresses regret about an action that was taken but, in retrospect, should not have been — this is the negative counterpart to "should have" (missed opportunity) and is used for criticizing a decision that did happen. "Couldn't have" (option A) expresses that something was impossible, which contradicts the fact that the deployment did happen. "Mustn't have" (option B) is not standard for expressing past regret about a decision — "mustn't" expresses prohibition, and it does not combine naturally with "have" in this deductive sense. "Wouldn't have" (option C) expresses a hypothetical outcome in a counterfactual conditional ("If we had known, we wouldn't have deployed"), not direct regret about an action that occurred, so it does not fit this single-clause context.