a. use the same grammatical construction in all similar headings throughout an outline
Using the same grammatical construction in all similar headings throughout an outline is called parallel construction. Parallel construction is also known as parallelism. This means that two or more ideas has the same degree of importance in the sentence therefore it should be written or stated grammatically equal. This can also help in establishing the clarity of the idea you want to convey in the sentence. Some examples of parallelism are the following :
of loving so much
of hating too hard
of crying so long
Why did settlers in Jamestown almost starve?
They lacked the basic farming techniques required to grow sustainable crops.
What was the name of the Native American girl who saved Smiths life? Whom did she marry?
Answer 1. Pocahontas saved John Smith's life.
Answer 2. Pocahontas married John Rolfe.