Dear RL:

You wrote:
>If I write:

>A series of promotional activities that RELATE/RELATES…..

>Kindly clarify.

You could use either verb depending on which word you want the adjective clause to modify.

The clause that begins “that relates” is an adjective clause. It could modify either “series” or “activities.” If you want it to modify “series,” then the verb would be “relates” since “series” is singular and “that” is the pronoun replacing “series.” However, if you want the clause to describe “activities,” then you would use the verb “relate” because “activities” is plural and the “that” would be standing for “activities.”

Generally, you would want to place the clause as close as possible to the word it modifies. That is not always possible–in this case because of the prepositional phrase “of promotional activities.” If the subject of the sentence were also plural, readers would assume that the clause modifies “activities.” But if you want the clause to modify “series,” then the verb “relates” would make it clear that the clause is describing the series, not the activities. You can make the distinction here because one noun is singular and one noun is plural.