知识点 1

Identify and fix sentence fragments, run-ons, and comma splices.

Recognize fragments, run-ons, and comma splices, then choose the boundary that makes the sentence complete.

核心知识

A complete sentence needs a subject, a verb, and a complete thought. Fragments are missing one of these. Run-ons and comma splices jam two complete sentences together without proper punctuation.

深入理解

Three boundary errors show up repeatedly on the SAT:

Comma splice: two independent clauses joined by just a comma.
→ "The experiment failed, the researchers tried again."

Run-on (fused sentence): two independent clauses with no punctuation at all.
→ "The experiment failed the researchers tried again."

Fragment: a group of words that looks like a sentence but lacks a subject, a verb, or a complete thought.
→ "Because the experiment failed." (dependent clause standing alone)

The fix for each is different:

  • Comma splice or run-on → add a period, semicolon, or comma + coordinating conjunction.
  • Fragment → attach it to a nearby independent clause or add the missing element.

On the SAT, you won't be asked to name the error. You'll just see four options for punctuating a passage, and only one avoids all three problems.

分步讲解

  1. Read the full sentence and identify each clause (look for subject-verb pairs).
  2. Ask: can each clause stand alone as a complete sentence?
  3. If two independent clauses are separated by just a comma → comma splice. If by nothing → run-on.
  4. If a dependent clause stands alone without an independent clause → fragment.
  5. Check the answer choices for correct boundary punctuation: period, semicolon, or comma + FANBOYS conjunction.

常见误解

  • "Long sentences are run-ons." Length doesn't matter—a 50-word sentence with proper punctuation is fine. A 10-word sentence can be a run-on.
  • "A comma is always enough between two clauses." A comma alone between two independent clauses is a comma splice. You need a conjunction with it.
  • "Starting a sentence with 'because' creates a fragment." Not necessarily—"Because she studied hard, she passed" is a complete sentence. It's only a fragment if the dependent clause stands alone.
题目

示例解析

While researching the cultural significance of jade in ancient Mesoamerican societies, archaeologist Dr. Sofia Gutierrez found that jade artifacts were not merely decorative ______ served as symbols of political power and spiritual authority across multiple civilizations.

Which choice completes the text so that it conforms to the conventions of Standard English?

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