Sentence Structure and Formation
What to know
Sentence-structure questions test whether a group of words is a complete sentence and whether clauses are joined correctly. A sentence needs a subject, a verb, and a complete thought. A fragment is missing one of these; a run-on joins two independent clauses with no punctuation or only a comma (comma splice). Fixes include a period, a semicolon, a comma plus a coordinating conjunction (and, but, or, so), or subordination (because, although, which). Also know parallel structure in lists, correct modifier placement, and punctuation of colons and dashes.
Traps
Comma splices often sound natural, so read for clause boundaries rather than rhythm. Dangling modifiers ("Walking to school, the rain began") are easy to miss. Long introductory phrases can hide the real subject, making a fragment look complete. In parallel lists, one mismatched item ("hiking, swimming, and to bike") is the error.
Rule of thumb
Underline every verb and ask who or what performs it. Then check each independent clause boundary: if two complete thoughts meet, they need more than a comma.
Worked example: "The researcher collected samples, she analyzed them that evening." Two independent clauses joined by a comma-a comma splice. Correct: "The researcher collected samples; she analyzed them that evening" or "The researcher collected samples, and she analyzed them that evening" or "After collecting samples, the researcher analyzed them that evening."