5 exercises — practise sequencing events with "by the time" and perfect tenses.
0 / 5 completed
1 / 5
Which sentence correctly uses "by the time" with the past perfect to describe an incident timeline?
"By the time the on-call engineer was paged, the error rate had already exceeded 50%" correctly uses the past perfect "had exceeded" for the event that happened earlier, relative to the simple past "was paged". Option B uses the simple past for both events, losing the sense that one happened before the other. Option C incorrectly uses the present perfect, which cannot anchor to a past time reference like "by the time... was paged". Option D drops the passive "was" needed since the engineer is paged by someone else.
2 / 5
Which sentence correctly uses "by the time" with the future perfect to describe a rollout plan?
"By the time the next release ships, the team will have migrated all services to the new SDK" correctly pairs the present simple in the time clause ("ships") with the future perfect in the main clause ("will have migrated") to show completion before a future point. Option B uses the plain future, which does not convey completion by that deadline. Option C incorrectly uses "will ship" inside a time clause, where English requires the present simple. Option D uses a gerund instead of the past participle after "will have".
3 / 5
Which sentence correctly uses "by the time" to contrast two past events in a postmortem, with the necessary tense difference?
"By the time we rolled back the deployment, the cache had already filled with corrupted entries" correctly places the past perfect in the main clause for the earlier event and the simple past in the time clause for the reference point. Option B loses the earlier-event meaning by using the simple past in both clauses. Option C incorrectly moves the past perfect into the time clause instead of the main clause. Option D incorrectly uses the present perfect, which does not fit a past time reference.
4 / 5
Which sentence correctly negates a completed state using "by the time" plus the past perfect in an incident report?
"By the time the alert fired, the health check had not yet detected the failing node" correctly uses "had not yet" with the past perfect to express that the detection had still not happened by that reference point. Option B uses the simple past instead of the past perfect, losing the required sequencing. Option C incorrectly uses the present perfect, which does not anchor to a past reference. Option D is missing the auxiliary "had" before the negator in the main clause and misplaces the perfect in the time clause.
5 / 5
Which sentence correctly uses "by the time" with the future perfect continuous to describe an ongoing process reaching a milestone?
"By the time the freeze lifts, the QA team will have been testing the release candidate for two full weeks" correctly uses the future perfect continuous to emphasize the ongoing duration of testing up to that future point. Option B uses the plain future continuous, which does not express completion of a duration by that deadline. Option C incorrectly uses "will lift" in the time clause, where the present simple is required. Option D uses the future perfect simple instead of the continuous, which is less natural for emphasizing an ongoing duration.