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Prepositions after verbs

Specify in or specify by?

Specify is usually followed by a direct object. In and by are used in different contexts around the verb.

Quick answer

How to use specify

Use specify something for the basic pattern. Specify in often refers to the place where details are stated, while specify by usually refers to a deadline or method.

Please specify the size in your order.
The terms are specified in the contract.
Applicants must specify by Friday whether they will attend.

Choose the pattern by meaning

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

1
specify + detail

Stating exact information

Specify commonly takes a direct object.

You must specify your requirements clearly.
2
specified in + document

Showing where details appear

Use in to refer to a document, law, form, or agreement containing the details.

Payment conditions are specified in the agreement.
3
specify by + time

Giving a deadline

By can introduce the latest time for providing information.

Please specify by Monday if you need accommodation.
4
specify by + method

Describing a means or standard

By can also describe the method used to define something.

The software allows users to specify by category.

See the difference in context

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

Construction
Example
Meaning
specify + object
Please specify your preferred date.
Standard pattern for giving exact information.
specified in + source
The rules are specified in the handbook.
Shows where information is written.
specify by + time
You must specify by noon.
Sets a deadline.
specify by + method
Results can be specified by region.
Shows classification or method.

Common mistakes

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

Using in directly after specify without a context

Specify usually needs an object before in.

✕ Please specify in the form. ✓ Please specify your address in the form.

Confusing by with a document reference

Use in for documents and written sources.

✕ The rules are specified by the contract. ✓ The rules are specified in the contract.

Quick practice

Choose the expression that matches the intended meaning.

1. The warranty terms are ___ the manual.
2. Please ___ your dietary needs.
3. Employees must respond ___ Thursday.

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Frequently asked questions

Can specify be used without a preposition?

Yes. The most common pattern is specify plus a direct object.

When do we use specified in?

Use it to show where information is written or recorded.

Is specify by correct?

Yes, especially for deadlines or methods, such as specify by Friday or specify by category.

sack, by, sack, for, sack, from "sacrifice for" or "sacrifice to"? sail from, in, for, to or through? "salvage from" or "salvage in"? sanction by, for, in, with or according? satisfy with, by, in, about or after? "saturate with" or "saturate in"? save by, for, from, on or in? "say in", "say about" or "say to"? "scan for", "scan in" or "scan through"? "scar by" or "scar on"? scatter in, across, around, throughout or on?

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