Peru State College
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Sentence Structure and Punctuation

Some Definitions

  • Clause: a group of words containing a subject and a predicate
  • Independent (Main) Clause: a clause that can stand alone as a sentence
    • I lost my hat.
  • Coordinating Conjunction: a word that joins two independent clauses
    • and, as, but, for, nor, or, so, yet
  • Dependent (Subordinate) Clause: a clause that cannot stand alone as a sentence because it contains a subordinating conjunction
    • before I put my keys away
  • Subordinating Conjunction: a word that appears at the beginning of a dependent clause and makes the clause unable to stand alone as a sentence
    • although, because, since, if, whenever

Three Basic Sentence Structures and Their Punctuation

  1. Simple Sentence

    Independent clause.

    • The umbrella is in the car.
  2. Compound Sentence

    Independent clause, coordinating conjunction independent clause.

    • It has begun raining since we arrived, and the umbrella is in the car.

    Note that the coordinating conjunction in a compound sentence is preceded by a comma.

  3. Complex Sentence

    Independent clause dependent clause.

    • It wouldn’t have started raining if I hadn’t left the umbrella in the car.

    Dependent clause, independent clause.

    • If I hadn’t left the umbrella in the car, it wouldn’t have started raining.

    Note that in a complex sentence, if the dependent clause precedes the independent clause, the two clauses are separated by a comma. However, if the independent clause comes first, no comma is necessary.


    Note: Sentences that combine compound and complex structures (compound-complex sentences) incorporate the punctuation appropriate to the type of conjunction.

Click on the links below for more writing tips:


Critical Thinking

Punctuation Pointers: Colons & Semicolons

Punctuation Pointers: Apostrophes & Quotation Marks

Writing Tips