When verbs serve parallel functions within a sentence, they should be treated with the same inflectional ending (-s/-es, -ed, or -ing) or should both have no inflectional ending at all. In each of the following examples, discussions explain this point in greater detail, and revisions illustrate adherence to this rule.
1. Below, we outline the main areas where the majority of companies are falling behind as well as highlighting insights and best practices from leading firms.
Here, the sentence erroneously suggests that falling and highlighting are corresponding verbs, but the verb that the latter word corresponds to is outline, and it should therefore also have no inflectional ending: “Below, we outline the main areas where the majority of companies are falling behind as well as highlight insights and best practices from leading firms.”
2. The document should describe company conformity and adherence to the principles as well as containing information about how the company will handle the issue.
The form of the verb following “as well as” should match that of the sentence’s first verb: “The document should describe company conformity with and adherence to the principles as well as contain information about how the company will handle the issue.” (Note, too, that conformity and adherence require distinct prepositions.)
3. This scale typically starts at level 1 and matures through levels 2, 3, and ultimately reaching level 4.
The verb preceding the final list item should match the others (note other revisions, too): “This scale typically starts at level 1, matures through levels 2 and 3, and ultimately reaches level 4.” (Reaching is correct if the sentence is revised as follows: “This scale typically starts at level 1 and matures through levels 2 and 3, ultimately reaching level 4.”)
