I believe you are talking about parallelism in lists - here is a quick explanation, hope it helps
In a list each of the items in the list must be in the same form - for instance a list of nouns or a list of verbs conjugated in the same way. You identify the list by the use of conjunctions, especially "and" and "or". when you see a conjunction you have to ask what things are being joined. It is often easiest to start with the thing that immediately follows the conjunction then read the sentence for meaning to determine which other items from the sentence are included in the list. Once you have a complete list then you must ensure that the items in the list are in the same form - if any items are not underlined then all of the other items must match that item.
For instance if the sentence says he chose sneakers and to wear shorts. there is a list that in the case of this uncorrected sentence contains sneakers and "to wear shorts" to fix this sentence both words have to be in the same form so sneakers and shorts. You could say to wear sneakers and shorts and in this case the "to wear" covers both nouns and it becomes a list of things he chose to wear, instead of a list of things he chose.
Special offer! Save $250 on GMAT Ultimate Classroom, GMAT Small Group Instruction, or GMAT Liveonline when you use the promo code GCVERBAL250. Or, save $150 on GMAT Self-Prep when you use the code GCVERBAL150. Enroll at www.princetonreview.com