Writing: Sentence Boundaries, Usage, and Revision
Sentence boundaries come first
Most Writing items test one of three structural errors: fragments (a word group without an independent clause), run-ons (two independent clauses fused with no punctuation), and comma splices (two independent clauses joined by only a comma). Fix run-ons and splices with a period, a semicolon, or a comma plus a coordinating conjunction (for, and, nor, but, or, yet, so). Fix fragments by attaching them to a nearby sentence or supplying the missing subject or verb.
Usage and clarity
Know subject–verb agreement when words sit between the subject and verb, pronoun–antecedent agreement including singular 'everyone,' 'anyone,' and 'each,' clear pronoun reference, and modifier placement - a modifier attaches to whatever noun it sits next to, which is how dangling modifiers create unintentionally funny sentences. Parallelism applies to lists, comparisons, and correlative pairs (not only... but also). Punctuation that appears most: commas around nonessential clauses (remove the clause; if the sentence still stands and the meaning is unchanged, use commas), semicolons between independent clauses only, colons after a complete clause introducing a list or explanation, and apostrophes for possession, not plurals.
Revision strategy
Prefer the shortest answer that keeps every idea and commits no error. Redundancy ('past history,' 'each and every') and wordiness are wrong even when grammatical.
Worked example
'I finished the draft, I emailed it to my editor.' Two independent clauses with a comma only - a splice. Correct: 'I finished the draft; I emailed it to my editor.' or '...draft, and I emailed...'