When a sentence contains a subject-verb agreement error, most often the problem is caused because the verb in the sentence is agreeing with a word that is not the actual subject-usually it is agreeing with a noun that is closer to the verb than the actual subject. We call this error the "nearest-noun" agreement error.
Let's look once again at the two examples of nearest-noun agreement errors that started the lesson. In Example 1, the verb is mistakenly agrees with the nearest noun entertainment system rather than the actual subject of the sentence advantages.
In Example 2, the problem is that the verb were mistakenly agrees with the nearest noun, cottages, rather than the actual subject of the sentence, one.
It is easy to make nearest-noun agreement errors when many words separate the subject of the sentence from the verb or when another noun comes between the subject of the sentence and the verb.