Prepositions after verbs

How to use affirm with prepositions

The verb affirm usually takes a direct object or a that-clause. Affirm in and affirm by are not common fixed patterns, although in and by may appear in related phrases.

Quick answer

Standard uses of affirm

Use affirm something or affirm that followed by a clause. Expressions such as affirm in and affirm by are uncommon as direct verb patterns and usually belong to other parts of the sentence.

The court affirmed the earlier decision.
She affirmed that the report was accurate.
The treaty was affirmed by all member states.

Choose the pattern by meaning

These forms are not interchangeable. Choose the construction by meaning, not by which preposition appears most often.

1
affirm + object

Confirming or supporting something

Use affirm directly before the statement, decision, or belief being confirmed.

The judge affirmed the ruling.
The company affirmed its commitment to safety.
2
affirm that + clause

Stating something firmly

Use affirm that to introduce a statement or claim.

Officials affirmed that the system was secure.
She affirmed that no rules had been broken.
3
affirmed by + agent

Showing who confirms something

By can appear in passive structures to identify the person or group doing the affirming.

The agreement was affirmed by the board.
The findings were affirmed by independent reviewers.
4
affirm in + phrase

Using in as part of another expression

In is not usually selected directly by affirm. It may belong to a following phrase such as in writing or in court.

He affirmed in writing that the data was correct.
The witness affirmed in court that she recognised the suspect.

See the difference in context

The same subject can take different constructions because each sentence answers a different question.

Construction
Example
Meaning
affirm in
She affirmed in writing that the contract was valid.
In usually introduces a separate phrase such as in writing or in court
affirm by
The decision was affirmed by the appeals court.
By commonly appears in passive structures
affirm + object
The leader affirmed his support for the plan.
standard active pattern without a preposition
affirm that
They affirmed that the data was reliable.
used to introduce a statement

Common mistakes

Some combinations appear in real text but do not mean what learners often assume.

Adding an unnecessary preposition after affirm

Affirm usually takes a direct object.

✕ She affirmed about her decision. ✓ She affirmed her decision.

Using affirm in as a fixed pattern

In normally belongs to another phrase, not directly to affirm.

✕ They affirmed in the proposal. ✓ They affirmed the proposal.

Confusing active and passive patterns

Use by mainly in passive constructions.

✕ The committee affirmed by the rule. ✓ The rule was affirmed by the committee.

Quick practice

Choose the expression that matches the intended meaning.

1. The court ___ the previous ruling.
2. The statement was ___ several experts.
3. She affirmed ___ the documents were authentic.

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Frequently asked questions

Is affirm in a common pattern?

No. In usually introduces a separate phrase such as in writing or in court.

When do we use affirm by?

Mostly in passive sentences, such as was affirmed by the court.

Can affirm be followed by that?

Yes. Affirm that is a common way to introduce a statement.

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