Verb Patterns with Verbs of Perception in Technical English
5 exercises — practise bare infinitive vs -ing after see/watch/hear/notice.
0 / 5 completed
1 / 5
Which sentence correctly uses the bare infinitive after a perception verb to describe a complete event that was observed from start to finish?
"...watched the deployment fail..." is correct: after perception verbs like "watch", the bare infinitive ("fail", without "to") is used when the observer perceived the entire event, from beginning to end, as described here by "from a config error to a full outage". Option B uses the -ing form, which would suggest witnessing only part of an ongoing process rather than its full course, which conflicts with the complete-event framing of the sentence. Option C incorrectly adds "to" before "fail", which is not permitted in this perception-verb pattern. Option D wrongly uses the finite present-tense form "fails" instead of the required bare infinitive.
2 / 5
Which sentence correctly uses the -ing form after a perception verb to describe an action observed in progress, without implying it was seen to completion?
"...noticed the CPU usage spiking..." is correct: the -ing form after a perception verb emphasizes catching an action mid-progress, without necessarily seeing its beginning or end, which fits "while I was reviewing the logs" — a background, ongoing context. Option A uses the bare infinitive "spike", which would suggest observing the complete spike event, but the sentence's framing suggests an incidental, in-progress observation instead. Option B incorrectly adds "to" before "spike", which perception verbs don't take. Option D uses the finite form "spikes", which isn't grammatical as a complement after "noticed" in this pattern.
3 / 5
Which sentence correctly uses "hear" + object + bare infinitive to describe a complete, momentary sound event?
"...heard the fan spin down completely..." is correct: the bare infinitive is appropriate here because the sentence describes hearing the entire process play out, reinforced by "completely", which signals a full, bounded event. Option B's -ing form would suggest catching only part of the winding-down sound rather than the whole completed process implied by "completely". Option C incorrectly adds "to" before the bare infinitive, which perception verbs never take. Option D wrongly uses the past participle "spun", which is not a valid complement form after "heard + object" in this active perception pattern.
4 / 5
Which sentence correctly contrasts the bare infinitive and -ing forms after "see" within the same sentence to mark two different types of observation?
"...saw the build finish successfully...seen it failing repeatedly for a week" is correct: the bare infinitive "finish" fits the single, complete successful run being reported as one bounded event, while the -ing form "failing" correctly conveys a repeated, ongoing pattern of failures observed over an extended period ("for a week"). Option B reverses this logic, using -ing for the single complete event and the bare infinitive for the repeated pattern, which doesn't match the intended meanings. Options C and D both incorrectly insert "to" before a perception-verb complement, which is never grammatical in this pattern.
5 / 5
Which sentence correctly uses "see" + object + bare infinitive in the passive voice, where "to" IS required?
"The service was seen to crash multiple times..." is correct: unlike the active voice pattern, when a perception verb like "see" is used in the passive voice, the following verb must take the to-infinitive ("to crash"), not the bare infinitive. Option A incorrectly keeps the active-voice bare infinitive pattern ("seen crash") in a passive sentence, which is ungrammatical. Option C garbles the sentence by using "saw" without the passive auxiliary "was" and without a logical subject performing the seeing. Option D incorrectly uses the active continuous form "was seeing", which changes the meaning and doesn't fit with a bare or to-infinitive complement here.