What is subject verb agreement?

Subject verb agreement is where the subject and the verb in the sentence go well with each other to where the sentence makes sense. For example: Sally runs on the street.
The subject is sally and the verb is run. They agree with each other.
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In addition: In the sentence "The girls runs in the playground" the subject and the verb do not agree in number. girls is a plural word, and runs is a singular form of the verb. For the subject and verb to agree, you would have to say "The girls run in the playground" or The girl runs in the playground. The subject and verb must agree in number and in person (see next paragraph).

Sometimes the relationship is a little trickier to find. In the question "How do the president enact laws?" changing the question into a statement will help. "The president do enact laws". President is third person singular, and 'do' is not third person singular. You would have to say "The president does enact laws" or The presidents do enact laws". Subjects and verbs must also agree in person. In question form, it becomes "How does the president enact laws?"

To run

Singular:
I run
You run
He, she, it, or Sally runs

Plural:
We run
You run
They, or the girls run

To do

Singular:
I do
You do
He, she, it, or the president does

Plural:
We do
You do
They, or the presidents do

How would you change this question so that subject and verb are in agreement? "Do smoking reduce your sex drive?"