Sentence Pattern 20: Using Parallel Structure To be done after SP 19
Review:

When you include two or more similar thoughts in the same sentence, they should be constructed in a similar way.  Similar construction is called "parallel structure."  There are many situations when parallel structure is used.  Here's a few:
1.  If one item in a series is listed as a prepositional phrase, the others should be in a prepositional phrase also.
    Example:  After a game of soccer, Bob quaffs a gallon of Gatorade, a quart of Quencher, and a pint of prune juice.  
    NOT: ...Bob quaffs a gallon of Gatorade, a quart of Quencher, and some prune juice.
2.  If one clause of a sentence is in ACTIVE voice, the other clause should also be in ACTIVE voice (not PASSIVE).  
    Example:  Bob participated in three events and won awards in all three.
    NOT:  Bob participated in three events and was awarded a prize in all three.
3.  If listing a series of actions (verbs) in a sentence, use the same verb tense.
    Example:  Whenever he feels melancholy, Bob runs on the beach, plays tennis, sees an upbeat movie, or calls a friend.   (All verbs are in present tense.)
    NOT:  ..., Bob runs on the beach, plays tennis, saw an upbeat movie, or calls a friend.  (Saw is in past tense.)
4.  There are lots of other situations in writing that require parallel structure.  It's hard to classify all of them.  Here's a few other examples of parallel structure.
    Right:  Fearing failure, Bob began trembling, sweating, and vomiting.
    Wrong:  ..., Bob began trembling, sweating, and he vomited.
    Right: Because Bob became an investigative reporter, he asked where the accident occurred, when it occurred, and why it occurred. 
    Wrong: ...., he asked where the accident occurred, when it occurred, and the reason it occurred.
      
Coordinate ideas must use the same tense or structure.  (These examples are taken from PUSD's Writing Manuel.)

Wrong: We learned how to change a tire, shift sixteen gears, and once almost ran the truck off the road.  
Correct: We learned how to change a tire, shift sixteen gears, and keep the truck from running off the road. 
  (All the objects of the verb learned are parallel.)
   
Wrong: I have mowed the lawn, washed the dog, rescued our hamster, and went to the store all in one day.
Correct:  I mowed the lawn, washed the dog, rescued our hamster, and went to the store all in one day. 
  (All the verbs are parallel)  
Wrong: Water skiing no longer interests me as much as to go scuba diving.  
Correct: Water skiing no longer interests me as much as scuba diving.  

New Info for Parallel Structure

Brought to you by the Purdue University Online Writing Lab.

For more information about sentence structure, see our workshop on this topic.
Parallel structure means using the same pattern of words to show that two or more ideas have the same level of importance. This can happen at the word, phrase, or clause level. The usual way to join parallel structures is with the use of coordinating conjunctions such as "and" or "or."

1. Words and Phrases

With the -ing form (gerund) of words:
 

Parallel: Mary likes hiking, swimming, and bicycling.

With infinitive phrases:
 

Parallel: Mary likes to hike, to swim, and to ride a bicycle.
OR
Mary likes to hike, swim, and ride a bicycle.

(Note: You can use "to" before all the verbs in a sentence or only before the first one.)

Do not mix forms.

Example 1

Not Parallel: Mary likes hiking, swimming, and to ride a bicycle.
Parallel: Mary likes hiking, swimming, and riding a bicycle.

Example 2

Not Parallel: The production manager was asked to write his report quickly, accurately, and in a detailed manner.
Parallel: The production manager was asked to write his report quickly, accurately, and thoroughly.

Example 3

Not Parallel: The teacher said that he was a poor student because he waited until the last minute to study for the exam, completed his lab problems in a careless manner, and his motivation was low.
Parallel: The teacher said that he was a poor student because he waited until the last minute to study for the exam, completed his lab problems in a careless manner, and lacked motivation.

2. Clauses

A parallel structure that begins with clauses must keep on with clauses. Changing to another pattern or changing the voice of the verb (from active to passive or vice versa) will break the parallelism.

Example 1

Not Parallel: The coach told the players that they should get a lot of sleep, that they should not eat too much, and to do some warm-up exercises before the game.
Parallel: The coach told the players that they should get a lot of sleep, that they should not eat too much, and that they should do some warm-up exercises before the game.
-- or --
Parallel: The coach told the players that they should get a lot of sleep, not eat too much, and do some warm-up exercises before the game.

Example 2

Not Parallel: The salesman expected that he would present his product at the meeting, that there would be time for him to show his slide presentation, and that questions would be asked by prospective buyers.
(passive)
Parallel: The salesman expected that he would present his product at the meeting, that there would be time for him to show his slide presentation, and that prospective buyers would ask him questions.

3. Lists after a colon

Be sure to keep all the elements in a list in the same form.

Example 1

Not Parallel: The dictionary can be used for these purposes: to find word meanings, pronunciations, correct spellings, and looking up irregular verbs.
Parallel: The dictionary can be used for these purposes: to find word meanings, pronunciations, correct spellings, and irregular verbs.

Proofreading Strategies to try:

HW: You are to write 6 sentences using all three examples twice.