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Use 'was' with a singular subject (The book was) and 'were' with a plural subject (The books were). Find the real subject, ignore introductory words and prepositional phrases, then match the verb to singular or plural.

Below: a clear rule, edge cases, many wrong/correct pairs, quick rewrite templates, and practical examples for work, school, and casual writing so you can fix sentences fast.

Quick answer

Match the verb to the subject: singular → was; plural → were.

Singular: The book was on the desk.
Plural: The books were on the desk.
If you can't find the subject, rewrite so the subject precedes the verb or substitute it/they to test: It was / They were.

Core rule (grammar): identify the real subject

Locate the noun or pronoun that controls the verb. Ignore prepositional phrases (on the desk), parentheticals, and introductory there/only/between. Then choose 'was' for singular subjects and 'were' for plural.

Single item → use 'was'. Multiple items → use 'were'.
Compound subjects joined by and are plural: The book and the pen were missing.
With or/nor, match the verb to the closest subject: Neither the books nor the pen was usable.

Wrong_right: Incorrect: The book were on the table.
Correct: The book was on the table.
Wrong_right: Incorrect: The books was missing.
Correct: The books were missing.
Wrong_right: Incorrect: The book and the report was submitted.
Correct: The book and the report were submitted.

Edge cases: collective nouns, compound subjects, inverted 'there' sentences

These constructions hide the true subject. Find that subject and let it dictate the verb.

Collective nouns (team, staff, family) take singular or plural verbs depending on meaning: as a unit → singular; as individuals → plural.
Inverted sentences (There is/are, fronted adverbials, questions) put the subject after the verb-use the number of the post-verb subject.
Compound subjects with or/nor follow the noun closest to the verb.

Wrong_right: Incorrect: The staff were unanimous in their decision. Correct (US formal): The staff was unanimous in its decision. Correct (UK/informal): The staff were unanimous in their decision.
Wrong_right: Incorrect: There was two books on the shelf.
Correct: There were two books on the shelf.
Wrong_right: Incorrect: Either the books or the pen were missing.
Correct: Either the books or the pen was missing.

How to fix your sentence: a step-by-step method (rewrite help)

Follow these steps for a quick, reliable fix.

1) Find the subject that the verb depends on.
2) Decide if that subject is singular or plural.
3) Use 'was' for singular, 'were' for plural.
4) If the structure hides the subject, rewrite the sentence so the subject comes before the verb.

Rewrite:
Original: Along with the notes, the book were missing. Fix: Along with the notes, the book was missing. Better: The book and the notes were missing.
Rewrite:
Original: There was a dozen books on the shelf. Fix: There were a dozen books on the shelf. Better: A dozen books were on the shelf.
Rewrite:
Original: The book, not the magazines, were useful. Fix: The book, not the magazines, was useful. Or: The book was useful; the magazines were not.

Real usage: ready-to-copy wrong/right pairs for work, school, and casual contexts

Choose the correct form that matches the intended number. The examples below are grouped by context.

Work:
Incorrect: The book was placed in the evidence locker.
Correct: The books were placed in the evidence locker.
Work:
Incorrect: The book was distributed to the whole team.
Correct: The books were distributed to the whole team.
Work:
Incorrect: The book was expected by the client.
Correct: The books were expected by the client.
School:
Incorrect: The book was cited three times in the literature review.
Correct: The books were cited three times in the literature review.
School:
Incorrect: The book was required reading for the course.
Correct: The books were required readings for the course.
School:
Incorrect: Why was the books listed under optional?
Correct: Why were the books listed under optional?
Casual:
Incorrect: The book were hilarious.
Correct: The books were hilarious.
Casual:
Incorrect: The book was all torn up. (when you mean multiple)
Correct: The books were all torn up.
Casual:
Incorrect: The book and the DVDs was left at my place.
Correct: The book and the DVDs were left at my place.

Try your own sentence

Test the whole sentence in context. Often the surrounding words make the correct verb clear.

Quick rewriting templates (copy-and-paste repairs)

Use these simple rewrites when structure hides the subject.

If 'there' confuses: Put the noun first - "Three books were on the desk."
If a long parenthetical separates subject and verb: Move the subject before the parenthetical or split the sentence.
If compound parts confuse: Break into two sentences or list items clearly.

Template: Problem: There was many mistakes in the report. Fix: Many mistakes were in the report. Or: The report contained many mistakes.
Template: Problem: The book, along with the notes, were missing. Fix: The book was missing, and so were the notes. Or: The book and the notes were missing.
Template: Problem: The books was left overnight. Fix: The books were left overnight.

Memory tricks and quick checks

Short tests to proofread fast.

Substitute it/they: "It was" vs "They were". If 'they' fits, use 'were'.
Insert a number: If "one" fits, use singular; if "two" fits, use plural.
Underline the true subject, not the first noun you see.

Check: Insert 'one' or 'two' - "one book was" vs "two books were."
Check: Move the subject next to the verb - the sentence will reveal the correct form.

Hyphenation, spacing and punctuation that matter (and what doesn't)

Formatting rarely changes number, but punctuation can hide the subject. Clean punctuation and consistent spacing make proofreading easier.

Hyphenation doesn't change singular/plural: The well-written book was praised / The well-written books were praised.
Commas and parentheticals can separate subject and verb; if they confuse you, rewrite.
Extra spaces don't alter grammar but slow scanning-keep spacing consistent.

Format: Incorrect scanning: The book , along with the notes , was left. Correct: The book, along with the notes, was left.
Format: Punctuation hides the subject: My favorite, the book that started it all, was sold. (Subject is 'the book' → 'was')

Similar mistakes to watch for

While checking subject-verb agreement, watch these related traps.

There is vs There are - identify the post-verb subject.
Uncountable nouns (information, equipment) take singular verbs: The information was helpful.
Pronoun agreement - plural nouns need plural pronouns: The books were dusty; they were covered in mold.

Wrong_right: Incorrect: There is many books on the syllabus.
Correct: There are many books on the syllabus.
Wrong_right: Incorrect: The information were inaccurate.
Correct: The information was inaccurate.
Wrong_right: Incorrect: The books was praised in its review.
Correct: The books were praised in their review.

FAQ

Should I use 'was' or 'were' after 'there'?

Use the verb that matches the noun after 'there'. If the following noun is plural, use 'were' (There were three books). If singular, use 'was' (There was a book).

Which is correct: 'The book was missing along with the pen' or 'The books were missing along with the pen'?

Both are correct depending on meaning. Use 'book was' for one book and 'books were' for multiple. If meaning is unclear, rewrite: 'The book and the pen were missing' or 'The books and the pen were missing.'

Is 'The staff were' wrong?

No-usage varies. In US formal writing 'staff' is often singular (The staff was). British and informal usage may treat staff as plural when referring to individual members (The staff were).

How do I fix long sentences where the subject is separated from the verb?

Move the subject next to the verb or split the sentence. Example: 'The book, along with the notes, was missing.' Or rewrite: 'The book and the notes were missing.'

Will a grammar checker always fix these errors?

Checkers catch many errors but can be misled by context (collective nouns, style choices). Use a checker as a helper and apply the subject-identification rule to confirm suggestions.

Want a quick check on a sentence?

Run the three-step check: find the subject, decide singular/plural, pick 'was' or 'were'. Search your draft for 'was' and 'were' and verify each occurrence; a few minutes of spotting saves common mistakes.