What is an adjectival clause? What are relative pronouns?
A subordinate clause that modifies a noun or pronoun is an adjectival clause.
An adjectival clause usually starts with a relative pronoun.
The relative pronouns are who (subjective), whom (objective), which, and that.
The relative pronoun plays a key role in the clause. It serves as the subject of the clause, the direct object of the clause, or the object of a preposition in the clause.
Examples
1. Clara Barton, who has become known for nursing, really spent most of her time in the Civil War procuring and organizing supplies.
Who has become known for nursing is the adjectival clause modifying Clara Barton.
Who is the relative pronoun, and it serves as the subject of the adjectival clause.
2. She organized the nurses about whom we have heard so much into the American Red Cross.
About whom we have heard so much is the adjectival clause. The relative pronoun whom is the object of the preposition about. The adjectival clause modifies nurses. Notice that the clause starts with the preposition and not the relative pronoun. This happens when the relative pronoun is the object of a preposition in the clause (for whom, about which, etc.).
3. This incredible organization that she began was based on the model of the International Red Cross.
That she began is the adjectival clause modifying organization. The relative pronoun which is the direct object of the clause (describes what she began).
How do I use "whose," "who," and "whom"?
The adjectival clause is sometimes introduced by the word whose. It serves as a pronominal (possessive) adjective in the subordinate clause.
Examples
1. Red Cross nurses, whose fame spread quickly during the Civil War, were responsible for saving many lives.
Whose fame spread quickly during the Civil War is the adjectival clause modifying nurses. Whose is a pronominal adjective in the clause, which modifies the subject of the clause, fame. The relative pronominal adjective relates the adjectival clause to the word nurses.
Many people are confused about when to use "who" and when to use "whom." Choose "who" when it is the subject of the adjectival clause. Choose "whom" when it is the direct object or object of a preposition in the adjectival clause.
Examples
1. Barton, who found herself criticized for her success, battled on.
Who is the subject of the adjectival clause.
2. The soldiers whom she helped were no doubt more grateful.
Whom is the direct object of the adjectival clause; she is the subject of that clause.