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English · Sentence Structure

Repairing a Run-On Sentence

Medium English Sentence Structure

Question

Read the sentence below and choose the option that best replaces the underlined portion. If the original is correct as written, choose 'NO CHANGE.'

The library closes at nine the students rushed to finish their group project.

Answer choices

  1. nine the
  2. NO CHANGE
  3. nine, so the
  4. nine; the,

C Correct answer: C) nine, so the

Both halves are independent clauses. The cleanest fix that also preserves the cause-effect relationship is a comma plus the coordinating conjunction "so": "The library closes at nine, so the students rushed to finish their group project."

The other options either introduce a grammatical error or change the intended meaning. The ACT consistently rewards the most concise, grammatically correct option.

Read the sentence with each option substituted in. The version that preserves meaning while obeying the underlying rule is the correct answer; on the ACT, that is almost always the shortest option that still works.

The underlying rule

Two independent clauses joined with no punctuation form a run-on (or "fused sentence"). They must be separated with a period, a semicolon, or a comma plus a coordinating conjunction.

Why each wrong answer is wrong

  • A) nine the: This option leaves the run-on uncorrected or introduces a different punctuation error.
  • B) NO CHANGE: This option leaves the run-on uncorrected or introduces a different punctuation error.
  • D) nine; the,: This option leaves the run-on uncorrected or introduces a different punctuation error.

Study tip

Whenever a sentence has two independent clauses jammed together, your three options are: period, semicolon, or comma + FANBOYS. Pick the one that best matches the relationship between the ideas.