1. The infinitive specifies: first or only to do what?
The first applicant is not yet a complete description: first in the queue, first alphabetically or first to apply? To submit the form names the event that establishes the order. It modifies the noun rather than expressing the purpose of the main action.
These constructions are natural after ordinal numbers, the last, the next, the only and superlative adjectives. They work in reports, biographical accounts and everyday conversation.
the first / second / last / next / only + noun + to + base form
- V1 / base form —
- The base verb without to: work, go, be.
- noun —
- A word naming a person, thing or idea: student, book, happiness.
Marta was the first applicant to submit the form.
Marta was the first applicant to submit the form.
Being first concerns submitting the form, not the position of a name on a list.
This is the smallest team to reach the final.
This is the smallest team to reach the final.
We compare the sizes of teams that reached this stage.
2. Structure: to + base form, without an extra who
In a simple active construction, the person or thing being described performs the infinitive action: in the researcher to identify the fault, the researcher identifies it. Use the base form after to, without -s, a past ending or -ing.
The full form who identified can become to identify when the context supports this modifier. Do not retain who before an ordinary to identify. The main verb of the sentence remains: She was the first researcher to identify the fault.
who / that + finite verb → to + base form (when the intended modifying meaning is preserved)
- verb / V —
- A word for an action or state, such as work or be. The pattern determines its form.
- V1 / base form —
- The base verb without to: work, go, be.
Leo was the second visitor who signed the book. → Leo was the second visitor to sign the book.
Leo was the second visitor who signed the book. → Leo was the second visitor to sign the book.
Replace the whole unit who signed with to sign; was remains.
The only device to work offline is this one.
The only device to work offline is this one.
Device performs the action work; do not add -s after to.
3. Do not confuse the infinitive form with the time of the event
To arrive does not automatically mean the future. In an account of yesterday, it can correspond to who arrived; in a schedule with next, it can describe someone still to arrive. The main verb and context establish the time.
To have + V3 explicitly marks earlier experience or completion before a reference point. However, not every past fact requires a perfect infinitive: She was the first to arrive yesterday is entirely natural.
to arrive — time supplied by context; to have arrived — explicitly completed earlier action
Nina was the last guest to arrive yesterday.
Nina was the last guest to arrive yesterday.
To arrive describes a completed past event here, not an intention.
You will be the next person to speak.
You will be the next person to speak.
Will be and next establish a future turn, not a completed speech.
He is the only member to have worked abroad.
He is the only member to have worked abroad.
To have worked explicitly presents previous experience; only alone does not determine the time.
4. Active, passive and the role of the noun
If someone performs the action, use to interview; if someone interviews them, use to be interviewed. Form the passive infinitive with to be + V3. When necessary, combine prior completion and the passive: to have been interviewed.
Do not arbitrarily remove the subject inside an object relative clause. In the first candidate that the panel interviewed, the candidate is the object of interview. The first candidate to interview the panel reverses the roles. To preserve the event, recast it in the passive: the first candidate to be interviewed by the panel.
agent: to + base form; recipient of the action: to be + past participle (V3); earlier passive action: to have been + V3
- V1 / base form —
- The base verb without to: work, go, be.
- V3 / past participle —
- The third verb form: worked, gone, seen. Used after have/has or in the passive, for example; it is not always the same as V2.
I was the first employee to interview the director.
I was the first employee to interview the director.
The employee asked the questions.
I was the first employee to be interviewed by the director.
I was the first employee to be interviewed by the director.
The employee answered the questions; by the director preserves the agent.
This is the only proposal to have been approved so far.
This is the only proposal to have been approved so far.
The proposal does not approve other things: the passive is preserved together with prior completion.
5. Order, uniqueness and negation convey different messages
First, last and next indicate a place in a sequence; only singles out one participant with a particular property. The only candidate to pass does not mean that there was only one candidate altogether: the others may have failed.
Negation applies to the action it precedes. The only person not to reply means that one person failed to reply, not that only one replied. Not to is a useful neutral order; to not is also possible and should not be declared ungrammatical.
Ravi was the only candidate to pass both tests.
Ravi was the only candidate to pass both tests.
Only restricts the group who passed both tests, not the total number of candidates.
Ravi was the only candidate not to sign the agreement.
Ravi was the only candidate not to sign the agreement.
Ravi alone did not sign.
6. Limits of reduction: a valid alternative is not an error
A full relative clause remains correct: the first person who arrived. If an exercise requests an infinitive, this answer does not meet the particular learning objective, but it is not grammatically incorrect.
The only candidate waiting outside is also grammatical: it describes someone currently waiting outside. The only candidate to pass describes a result. Only itself does not prohibit -ing; the meaning relationship matters. Do not turn every relative clause into an infinitive: the colleague who lives upstairs does not automatically mean the colleague to live upstairs.
Modality cannot simply be deleted either: the only colleague who might know the answer expresses uncertainty. The only colleague to know the answer presents the knowledge as a fact. If the concise version loses a necessary nuance, retain the full clause.
She was the first person who noticed the leak. / She was the first person to notice the leak.
She was the first person who noticed the leak. / She was the first person to notice the leak.
Both versions describe the same event; the infinitive version is concise, not the only correct option.
The only candidate waiting outside has a blue folder.
The only candidate waiting outside has a blue folder.
Waiting describes an ongoing situation. Only does not make it incorrect.
She is the only colleague who might know the password.
She is the only colleague who might know the password.
Might preserves uncertainty; mechanically substituting to know would remove it.
7. Using the structure: concise descriptions without losing facts
First identify whom or what you are describing, which property you are comparing and whether the event has already happened. Then check who performs the action and whether a passive is needed. Only then choose a concise infinitive construction.
Do not force an infinitive into every sentence of your own writing. One expression such as the first team to… can convey the key fact, while the following sentence explains its cause or consequence. Personal facts are unnecessary: you can describe an imaginary situation.
Our office was the first branch to introduce evening appointments. The change helped people who work during the day.
Our office was the first branch to introduce evening appointments. The change helped people who work during the day.
The first modifier is reduced to express priority; the second full relative clause is naturally retained.
Who will be the next person to present? We need to check the running order.
Who will be the next person to present? We need to check the running order.
The infinitive phrase also works in a question; will be establishes the future order.
Common mistakes
Incorrect:She was the only applicant to meeting the deadline.
Correct:She was the only applicant to meet the deadline.
In this infinitive construction, to requires the base form meet, not meeting.
Incorrect:He was the first visitor who to arrive.
Correct:He was the first visitor to arrive.
Remove who for this reduced form; who arrived would be a separate valid alternative.
Incorrect:This was the first building to be build on the site.
Correct:This was the first building to be built on the site.
The passive requires the past participle built after to be: the building receives the action rather than performing it.
Incorrect:She is the youngest researcher to has won the prize.
Correct:She is the youngest researcher to have won the prize.
Even in a perfect infinitive, use the base form have after to, not has.
Sources
- British Council — 'to'-infinitives: article and Peter M.’s answers on ordinal numbers, superlatives and time in context
- Cambridge English Grammar Today — Infinitive: active or passive?
- Cambridge English Grammar Today — Perfect infinitive
- Cambridge English Grammar Today — Negation in non-finite clauses: not to / to not