Infinitive and -ing clauses
Non-finite clauses package actions or states without an independent tense and function as subjects, complements or modifiers.
01 · Concept foundation
Understand the terms before applying the rule
Each term below names a different grammatical object. Open examples and compare their function rather than memorising a Vietnamese translation alone.
infinitive clause/ɪnˈfɪnətɪv klɔːz/
mệnh đề nguyên mẫuA non-finite clause built around to + base verb or a bare infinitive.
to reduce uncertainty
để giảm độ bất định
-ing clause/ˈɪŋ klɔːz/
mệnh đề -ingA non-finite clause built around an -ing form and functioning as a complement, subject or adjunct.
Monitoring waves requires equipment.
Giám sát sóng cần thiết bị.
understood subject/ˌʌndəˈstʊd ˈsʌbdʒɪkt/
chủ ngữ ngầm hiểuThe semantic subject of a non-finite clause, recovered from context or a controlling expression.
The team aims to reduce error. Subject of reduce: the team
Nhóm nhằm giảm sai số. Chủ thể của reduce: nhóm
Complete lesson scope
Do not stop at one formula
To-infinitive, bare infinitive and -ing clauses
Perfect, progressive and passive non-finite forms
Control, raising and understood subjects
Verb/adjective/noun complementation and purpose clauses
Decision boundary: The controlling word and intended meaning determine the non-finite form; translation alone is unreliable.
02 · Controlling rule
Non-finite clauses do not carry independent tense. Their form is licensed by a controlling verb, adjective, noun or preposition and by meaning. To-infinitives commonly express intention, purpose, potential or a selected complement; V-ing clauses construe an event as an activity, fact or process and follow prepositions; bare infinitives follow core modals and certain causative or perception verbs. Perfect forms mark anteriority, while passive forms mark an affected understood subject. Some verbs allow more than one form with a change of meaning.
to do | to be doing | to have done | to be done | doing | having done | being done | having been done | bare doInfinitive and -ing clauses: form, control and meaning
Select to-infinitive, bare infinitive, V-ing, perfect and passive non-finite forms according to the controlling verb/adjective/noun, intended time relation, voice and meaning change.
A non-finite form is selected by grammar and meaning together. The matrix word licenses a pattern, while aspect and voice show whether the embedded event is simultaneous, earlier, ongoing or received.
To-infinitive often presents a projected, intended or selected event; V-ing often presents an activity as a process, experience or fact. Bare infinitive follows core modals and certain causative/perception patterns. Perfect and passive forms add time and voice without creating a finite tense of their own.
Which word controls the complement: a verb, adjective, noun or preposition?
Is the understood subject the matrix subject, the object or a separately expressed noun phrase?
Does the embedded event occur at the same time, earlier, later or as a purpose/result?
Is the embedded participant performing or receiving the action?
1. Core non-finite form system
English has several non-finite verb phrases, each with active/passive and simple/perfect contrasts.
to do · to be doing · to have done · to be done · to have been done · doing · having done · being done · having been done · bare doSimple to-infinitive commonly expresses an event simultaneous with or later than the matrix event.
Perfect infinitive/gerund marks an earlier event: to have completed, having completed.
Passive non-finite forms show the understood subject receives the action: to be measured, being measured, having been measured.
Bare infinitive follows modals and active make/let, and may follow perception verbs for a complete event.
The team expects to complete the calibration by Friday.
The team expects to complete the calibration by Friday.
To complete presents a projected event after the expectation.
The model appears to have underestimated the peak.
The model appears to have underestimated the peak.
Perfect infinitive places the underestimation before the current appearance/inference.
To-infinitive family
to do · to be doing · to have done · to be done · to have been doneExpress projected/complement meaning with optional progressive, perfect or passive contrasts.
to measure
to be measuring
to have measured
to be measured
to have been measured
- The infinitive has no independent finite tense; time is interpreted relative to the matrix clause.
V-ing family
doing · having done · being done · having been doneConceptualise activity/process, earlier completion or passive reception.
measuring
having measured
being measured
having been measured
- After a preposition, use V-ing rather than a to-infinitive unless to is part of an infinitive marker.
Bare infinitive
modal/make/let/perception + (object) + base verbComplete modal, causative and selected perception structures.
can measure
made the model converge
saw the gate open
- Passive make restores to: The model was made to converge.
remember doing versus remember to do
I remember checking the sensor.
Memory of an earlier check.
Remember to check the sensor.
Instruction not to forget a future action.
Ask whether the embedded action is remembered as past experience or remains to be performed.
try doing versus try to do
Try reducing the time step.
Test this method as a possible solution.
Try to reduce the time step.
Make an effort to achieve the reduction.
V-ing proposes an experiment; to-infinitive emphasises effort toward a goal.
perception + bare infinitive versus V-ing
We saw the gate close.
The complete event was perceived.
We saw the gate closing.
The event was perceived in progress.
Choose by viewpoint on the event boundary, not by tense alone.
Conversation and IELTS Speaking
- Prefer
- Use common verb patterns and purpose infinitives to explain plans, preferences and reasons naturally.
- Avoid
- Rare perfect/passive stacks unless the time relation truly needs them.
- Why
- Fluent speech depends on automatic control of high-frequency patterns.
IELTS Writing Task 2
- Prefer
- Use infinitives for aims/solutions and V-ing clauses to nominalise activities when the reference is clear.
- Avoid
- Stringing several non-finite clauses together with hidden subjects.
- Why
- Controlled compression improves range; uncontrolled compression reduces clarity.
Technical instructions and methods
- Prefer
- Use explicit purpose, control and passive form: to measure, for operators to verify, to be calibrated.
- Avoid
- Ambiguous purpose clauses that seem to modify the wrong subject.
- Why
- Technical prose must make actor, action and sequence recoverable.
Do not translate markers mechanically: reconstruct the relation and viewpoint
Complement form selection
The controlling word often requires a specific form: decide to do, avoid doing, prevent O from doing.
Vietnamese often uses an uninflected verb sequence or để/mà without the same lexical form restriction.
Learn English verb plus pattern as one lexical unit rather than translating each verb separately.
Understood subject
Non-finite clauses often have a grammatically controlled understood subject.
Serial verb constructions may rely more heavily on context and discourse topic.
When translating into English, state the controller explicitly if two participants could perform the action.
Non-finite form and time/voice map
Interpret time relative to the matrix verb, not as an independent tense.
| Relation | Active | Passive |
|---|---|---|
| simple/simultaneous-later | to do / doing | to be done / being done |
| earlier/perfect | to have done / having done | to have been done / having been done |
| modal/causative | bare do | be made to do |
High-frequency verb patterns
This table is a starting point; dictionary evidence remains necessary for unfamiliar verbs.
| Pattern | Common verbs | Example |
|---|---|---|
| verb + to V | decide, plan, aim, hope, refuse | They decided to extend the test. |
| verb + V-ing | avoid, consider, finish, suggest | They considered extending the test. |
| verb + O + to V | advise, allow, enable, require | The tool enables users to compare runs. |
| verb + O + bare V | make, let, see, hear | We saw the gate close. |
✕ The team suggested to repeat the test.
✓ The team suggested repeating the test. / The team suggested that the test be repeated.
Suggest normally takes V-ing or a that-clause, not a to-infinitive.
✕ The method avoids to introduce bias.
✓ The method avoids introducing bias.
Avoid takes a V-ing complement.
✕ The new setting made the model to converge.
✓ The new setting made the model converge.
Active make uses object + bare infinitive.
✕ The model appears to underestimated the peak.
✓ The model appears to have underestimated the peak.
An earlier event after appears requires a perfect infinitive.
Choose by relation, viewpoint and discourse role
1. Which form follows avoid?
2. Which sentence means testing a possible method?
3. Which form shows an earlier passive event?
4. Which active causative is correct?
Write six sentences: purpose, verb + to-infinitive, verb + V-ing, object + to-infinitive, bare infinitive and a perfect/passive non-finite form. For each, identify the controlling word, understood subject and time relation.
The controlling word licenses the chosen complement.
The understood subject is unambiguous.
Simple/perfect and active/passive meaning are correct.
Any meaning-changing verb pattern matches the intended event relation.
03 · Worked examples
Observe form, function and meaning together
The team decided to extend the calibration period.
Nhóm quyết định kéo dài giai đoạn hiệu chỉnh.
The method avoids introducing unnecessary parameters.
Phương pháp tránh đưa vào các tham số không cần thiết.
The model appears to have underestimated the tidal range.
Mô hình dường như đã đánh giá thấp biên độ thủy triều.
Being exposed to salt water accelerates corrosion.
Việc bị tiếp xúc với nước mặn làm tăng tốc độ ăn mòn.
Having completed the quality check, the team released the dataset.
Sau khi hoàn thành kiểm tra chất lượng, nhóm đã công bố bộ dữ liệu.
The supervisor made the team repeat the simulation.
Người hướng dẫn yêu cầu nhóm chạy lại mô phỏng.
04 · High-risk contrast
Explain why one form fails, not only which answer is correct
The team suggested to repeat the test.
The team suggested repeating the test.
Suggest does not normally license a to-infinitive directly. It takes an -ing clause, a that-clause, or in some varieties a noun phrase plus should-clause. The form is a lexical property of the controlling verb, not a free stylistic choice.
05 · Mastery check
Apply the rule before marking the lesson complete
Which sentence is grammatically acceptable in the target system?
Which description best defines “infinitive clause”?
Which example is one of the verified target patterns in this lesson?
Which structural formula belongs to this lesson?
Complete all four checks, then submit a sentence for target-form feedback.
06 · IELTS Academic
Transfer grammar into a real communicative task
In Speaking, infinitive and -ing patterns make preferences, plans and experiences natural, but accuracy depends on the governing verb. In Writing, non-finite clauses express purpose, compress repeated subjects and build academic noun phrases. Use perfect and passive forms only when the time or voice distinction contributes real meaning; unnecessary compression can make a sentence harder rather than more advanced.
Choose to-infinitive, V-ing or bare infinitive from the controlling word and intended meaning.
Form simple, progressive, perfect and passive non-finite clauses accurately.
Explain meaning changes in high-risk pairs such as remember, stop, try, regret and mean.
Keep the understood subject clear and avoid an infinitive or -ing form chosen only by Vietnamese surface wording.