The subject (S) of a sentence can often be identified by asking a question beginning with who or what:
Amy laughed.
Q. Who laughed?
A. Amy (= S)
The house is very old.
Q: What is very old?
A: The house (= S)
In addition, the subject of a sentence has the following grammatical properties:
1 Subject–verb inversion. In a declarative sentence the subject comes before the verb:
Declarative: James (S) is (V) at school.
When we change this to an interrogative sentence, the subject and the verb change places
with each other:
Interrogative: Is (V) James (S) at school?
2 Subject–verb agreement. The subject of a sentence agrees in
number (singular or plural) with the verb which follows it.
Compare:
Singular subject: The dog barks all night.
Plural subject: The dogs bark all night.
Here, the form of the verb (barks or bark) is determined by
whether the subject is singular (the dog) or plural (the dogs). This
is known as subject–verb agreement.
However, subject–verb agreement only applies when the verb has a
present-tense form. In the past tense, there is no agreement with
the subject:
Singular subject: The dog barked all night.
Plural subject: The dogs barked all night.
Furthermore, agreement applies only to third-person subjects. For
instance, the same verb form is used whether the subject is I (the
first-person singular) or we (the first-person plural):
Singular subject: I sleep all night.
Plural subject: We sleep all night.
Amy laughed.
Q. Who laughed?
A. Amy (= S)
The house is very old.
Q: What is very old?
A: The house (= S)
1 Subject–verb inversion. In a declarative sentence the subject comes before the verb:
Declarative: James (S) is (V) at school.
When we change this to an interrogative sentence, the subject and the verb change places
with each other:
Interrogative: Is (V) James (S) at school?
2 Subject–verb agreement. The subject of a sentence agrees in
number (singular or plural) with the verb which follows it.
Compare:
Singular subject: The dog barks all night.
Plural subject: The dogs bark all night.
Here, the form of the verb (barks or bark) is determined by
whether the subject is singular (the dog) or plural (the dogs). This
is known as subject–verb agreement.
However, subject–verb agreement only applies when the verb has a
present-tense form. In the past tense, there is no agreement with
the subject:
Singular subject: The dog barked all night.
Plural subject: The dogs barked all night.
Furthermore, agreement applies only to third-person subjects. For
instance, the same verb form is used whether the subject is I (the
first-person singular) or we (the first-person plural):
Singular subject: I sleep all night.
Plural subject: We sleep all night.
