Two or more items in a series, whether they occur in a sentence, in a list, or throughout a paper (e.g., a series of headings), must be checked for parallel structure. Parallel structure means that the items are the same part of speech. Use these steps to check for parallel structure and correct faulty parallelism.

1. Identify the items in the series. If the items are not already in a list, look for conjunctions within sentences, since these often conjoin items that need parallel structure. It is often easier to spot faulty parallelism if you isolate the items and place them in a vertical list as you check them for parallel structure. Using a list at this stage makes it easier to compare the items.

   Example: To keep horses at home, the owner must commit a significant amount of time to daily care and knowing how to identify signs of illness or injury in the horse.

   Here we have two verb phrases conjoined by and. Therefore, the items that need parallel structure are as follows:

   	must commit a significant amount of time to daily care
   and	knowing how to identify signs of illness or injury in the horse

2. Check to see if the items are the same part of speech and if they use the same form. In this case, both items are verbs or verb phrases. However, they are not in the same form. The first one is the uninflected form must commit; the other is the present participle form knowing.

3. If the items are not the same part of speech and the same form, change the items so that they are.

   Revision:		must commit a significant amount of time to daily care
   	and	must know how to identify signs of illness or injury in the horse

   Note that words that appear in the beginning of all of the series items can sometimes be deleted after the first occurrence. In this case, must does not have to appear twice. We can instead reanalyze the list as consisting of two verbs that follow must: commit and know. Both verbs are now in the infinitive form.

   Revision: To keep horses at home, the owner must commit a significant amount of time to daily care and know how to identify signs of illness or injury in the horse.

   Sometimes more complex lists require another approach. Consider the following sentence:

   Example: The horses need to be groomed, watered, fed, and clean their stalls.

   Isolating the items in the series results in this list:

   	groomed
   	watered
   	fed
   and	clean their stalls

   The first three items are all past participle forms referring to actions that must be performed on the horses. The fourth is an uninflected form referring to an action that must be performed on the stalls. Therefore, we cannot simply change the fourth form to the past participle cleaned and stop there. The best way to fix this sentence is to revise it so that it contains two clauses:

   Revision: The horses need to be groomed, watered, and fed, and their stalls need to be cleaned.

   Now we have a series of two parallel clauses. Within the first clause, we also have a series of three parallel items. The following list format may help you to see these features.

   The horses need to be
   	groomed
   	watered
   and	fed
   and	their stalls need to be cleaned

Remember: To create parallel structure, first isolate the items in a series, then check their forms for consistency and make any needed revisions.

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