Grammar: Parallel Structure
Probably the most common error involving parallel structure occurs with lists. When you write a sentence that consists of a list or series of items, make sure they are written in the same grammatical form. The use of parallel structure makes your writing more consistent and clearer to your reader.
Faulty parallel structure: To sell her proposal, the marketing director presented her marketing plan, asked for reactions to her presentation, and many other things to involve her audience.
Better: To sell her proposal, the marketing director presented her marketing plan, asked for reactions to her presentation, and did many things to involve her audience.
Faulty parallel structure: The personnel director was requested to handle terminations of employees as well as writing commendations.
Better: The personnel director was requested to handle terminations of employees as well as to write commendations.
Faulty parallel structure can be corrected no matter what part of speech the items in a series are. The important thing to remember is to be consistent with the grammatical form you use for writing items in a series.
