Parallel Structure


Faulty Parallelism
If two or more ideas are parallel, they are easier to read and to understand when expresses in parallel grammatical form.  Single words should be balanced, phrases with phrases, clauses with clauses. 
Notice the following sentence:
    "Abused children commonly exhibit one or more of the following symptoms;  withdrawal, rebelliousness, restlessness, and they were depressed. (depression)
Notice that the writer used a noun (withdrawal) followed by a noun (rebelliousness), then the writer switched to a clause (they were depressed).  The writer needed to use a parallel structure, meaning that all the words in the sequence should be parallel.
Here is another example:
       Maria is responsible for stocking merchandise, writing orders for delivery, and sales of computers."  (selling)   
Notice that "sales of computers" does not match the gerunds: "writing," and "stocking." Thus we have to change it to "selling."
Have you gotten the idea?
Well, here is another example:

     "At San Jose High School, vandalism can result in suspension, or even being expelled from school." (expulsion).

All nouns: "suspension" and "expulsion."