A parallel structure refers to a type of grammatical structure in which elements of the same importance are presented using the same grammatical form or pattern in a sentence. In the sentence stem presented "He was sitting, reading, and..." there is a repetition "-ing" or gerund forms and therefore parallelism can be created if the last element includes this grammatical pattern. This means, adding planning, considering or eating would create parallelism, but adding a "thought about the book" does not create parallelism because this breaks with the repetition of the same grammatical structure that is necessary for parallelism.
To practice using formal and informal style, write two short paragraphs in your journal summarizing a topic on the Civil War (3-4 sentences). Write one paragraph as if you are writing for a textbook on the Civil War. Write the second paragraph as if you creating a video script for young kids to get them interested in the Civil War.
