Some Helpful Tools
Below are rules to show you how to use the definite relative pronouns.
The relative pronoun that can refer to people, animals, and things.
Definite Relative Pronoun - That
Horses that race get a lot of exercise.
The meaning of our sentence has been changed from a specific group of race horses to horses in general.
Since the relative clause is important to the sentence, no comma is needed as shown again in our example below:
That refers to a specific group of horses.
Since all horses are not race horse, this only refers to the specific group of horses that are race horses.
Horses get a lot of exercise.
Using our rule from earlier, if the relative clause that race is important to the sentence, we do not need a comma.
Let's see what happens when we remove the relative clause from the sentence.
Horses that race get a lot of exercise.
The relative pronoun which does not refer to people.
Definite Relative Pronoun - Which
Horses, which can be trained to race, will get lots of exercise.
Horses, which can be trained to race, will get lots of exercise.
Which, in this case, refers to horses in general that are trained.
Those horses will get lots of exericse. Not just the specific group of race horses.
If we remove the relative clause which can be trained to race out of the sentence, we would have:
Horses will get lots of exercise.
The meaning of our sentence has been changed.
However, since our relative clause which refers to a general group of horses, not just horses that are specifically race horses, we would add a comma.
Example 1:
Definite Relative Pronouns - Who and Whom
Reminder: Clauses that are enclosed in commas may be removed from the sentence without changing the meaning of the sentence.
Relative pronouns, such as who, that, and which are often found confusing.
Mary saw her neighbor who just bought a new sports car.
The relative pronoun who is the subject of bought.
The students, four of whom were tardy, participated in the event.
We use whom because it is the object of the preposition of.
Charlie was not sure whom he would offer the part in the play.
Whom can be substituted for the object pronoun him or her.
Charlie would offer him the part in the play.
Charlie would offer her the part in the play.
Since both make sense, use the pronoun whom.
Example 2:
Example 3:
Mary saw her neighbor who just bought a new sports car.
If who, whom, or whose introduces an essential or necessary relative clause, then no comma is placed in front of the relative pronoun.
The relative clause who just bought a new sports car is important to the sentence.
This means that Mary did not just see any neighbor in general.
Mary specifically saw the neighbor who just purchased the new sports car.
Since this relative clause is important to the sentence, we do not need a comma.
Example 4:
The students, who happen to be best friends, participated in the event.
The relative clause who happen to be best friends is added information.
Therefore, we do need a comma because that information is not needed.
The easiest of the three who and whom are used to refer to people. If the pronoun is the subject of the verb, then use who.
Language Arts: Definite Relative Pronouns
