English Grammar, Punctuation, and Usage
Core areas
Expect questions on subject–verb agreement, pronoun case, modifier placement, parallelism, tense consistency, and the punctuation of clauses. Know restrictive versus nonrestrictive elements, and the jobs of commas, semicolons, colons, dashes, hyphens, apostrophes, and quotation marks. Usage covers commonly confused pairs such as affect/effect, principal/principle, and ensure/insure, plus the formal register expected in a transcript.
Traps
Watch for comma splices and fused sentences; dangling and misplaced modifiers; "between you and I"; who versus whom; that versus which; commas wrongly set around restrictive clauses; apostrophe errors in plurals; and missing hyphens in compound modifiers. Remember that split infinitives and sentence-ending prepositions are not errors.
Worked example
Compare "The witness, who had waited two hours, was dismissed" with "The witness who had waited two hours was dismissed." In the first, the commas mark a nonrestrictive clause: there is one witness, and the clause adds extra information. In the second, the clause identifies which witness, so it is restrictive and takes no commas. Test: if removing the clause does not change which person or thing is meant, set it off with commas.
Rule of thumb
Punctuate for meaning, not for breath. Read the sentence without the clause and ask whether the identity changes.