Sentence Structure: Complete Sentences, Joins, and Parallel Form
What the test rewards
Sentence-structure questions ask two things: does this group of words form a complete sentence, and do its parts fit together logically? Start by locating the subject and the working verb of every clause. A clause needs both; a phrase has neither. If a word group lacks a subject, lacks a finite verb, or opens with a subordinator such as although, because, or which and never resolves into a main clause, it is a fragment.
Two complete clauses cannot be joined by a comma alone; that is a comma splice. They also cannot be joined with no punctuation at all, which is a run-on. Legal joins are a comma plus a coordinating conjunction (and, but, or, nor, for, so, yet), a semicolon, or a rewrite that makes one clause dependent. A conjunctive adverb such as however or therefore does not join clauses by itself; it needs a semicolon before it and usually a comma after it.
Traps to watch
- The long fragment: length does not make a sentence. The team having finished the audit before noon. is still a fragment.
- The comma-plus-however splice.
- Faulty parallelism: items in a list or pair must share grammatical form. She likes hiking, swimming, and to bike should be ...and biking.
- Dangling modifiers: an opening modifier must describe the subject that immediately follows the comma.
Worked example
Walking to the store, the rain soaked my jacket. The rain was not walking. Repair by naming the real actor after the comma: Walking to the store, I was soaked by the rain.
Rule of thumb: cover the comma. If the words on each side can stand alone as sentences, a comma is not enough to join them.