Subject-verb CONCORD relates to number agreement (singular/plural) between the subject-verb. There are 2 important restrictions to Subject and verb agreement. First, agreement applies when the verb is in the present tense. In the past tense, there is no clear agreement between the Subject-verb, for example, The dog barked all night, The dogs barked all night. Second, agreement applies only to 3rd person subjects. There is no difference, for example, between a 1st person singular Subject and a 1st person plural Subject, for example, I sang all night, We sang all night.
The concept of NOTIONAL AGREEMENT sometimes comes into play: where the verb form is not ascertained by the subject form. Instead, it is ascertained by how we interpret the Subject, for example, The government is considering the proposal, The government are considering the proposal. In the 1st, In government... the subject is construed as a unit that requires a specific verb form. In the 2nd, The subject is... perceived as having a plurality in the government, since it involves a set of individuals