Rachel · Class 02 · September 19, 2026

Sentence Boundaries · Class Notes

Find the main subject and its finite verb group before choosing punctuation.
Bracket phrases and relative clauses that modify the subject.
An independent clause has a complete subject–predicate core; a comma alone cannot join two independent clauses.

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Sentence-core notes · annotated classroom excerpt

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Apply 1 · A long subject is still one subject

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B. The core is The natural and mechanical materials / highlight these two aspects of his background.

That Palma Rodríguez uses in his art modifies materials. The finite verb uses belongs to that relative clause; highlight is the main predicate. Do not place a comma between this long subject and highlight.

A separates the subject from its predicate. C and D incorrectly place a comma before the restrictive that-clause.

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The natural mats that artist Palma uses in his art hightlight two aspects.

The natural mats, artist Palma uses in his art, hightlight two aspects.

Clarification: omitting the object relative pronoun that does not turn the clause into a parenthetical insertion. Keep the restrictive version unpunctuated: The natural materials the artist uses in his art highlight two aspects. A supplementary version needs which: The natural materials, which the artist uses in his art, highlight two aspects.

Try it 7 · Repair a comma splice

The first result was inconclusive, after checking the equipment, the researchers repeated the trial.

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The first result was inconclusive; after checking the equipment, the researchers repeated the trial.

First core: the first result / was inconclusive.
Second core: the researchers / repeated the trial.
After checking the equipment belongs with the second core. The boundary comes before that opening phrase.

A finite verb can appear inside a dependent clause. An -ing form, infinitive, or participle does not automatically supply a main predicate. An appositive is a noun phrase that renames a noun; it is not any clause placed between commas.