Subjects and verbs must AGREE with one another in number (singular or plural). Therefore, if a subject is singular, its verb must also be singular.; if a subject is plural, its verb must also be plural.
In the present tense, nouns and verbs form plurals in opposite ways: nouns ADD an s to the singular form; verbs REMOVE the s from the singular form
In the present tense, nouns and verbs form plurals in opposite ways: nouns ADD an s to the singular form; verbs REMOVE the s from the singular form
These agreement rules do not apply to verbs used in the simple past tense without any helping verbs.
The agreement rules do, however, apply to the following helping verbs when they are used with a main verb: is-are, was-were, has-have, does-do
The agreement rules do not apply to has-have when used as the SECOND helping verb in a pair.
They do NOT apply to any other helping verbs, such as can, could, shall, should, may, might, will, would, must.
The subject-verb agreement rules apply to all personal pronouns except I and you, which, although SINGULAR, require PLURAL forms of verbs
Compound nouns can function as a “compound subject.” In some instances, a compound subject poses special problems for the subject-verb agreement rule (+s, -s)
However, instead of using two sentences (as above), we may choose to give the above information in one sentence.
This sentence makes use of a compound subject (two subject nouns joined by and), illustrating a new rule about subject-verb agreement.
Although each part of the compound subject is singular (ranger and camper), taken together (joined by and), each one becomes a part of a plural structure and, therefore, must take aplural verb (see) to agree in the sentence.
SUBJECT-VERB RULE #1 – Two or more singular (or plural) subjects joined by and act as a plural compound subject and take a plural verb (singular + singular = plural).
You can check the verb by substituting the pronoun they for the compound subject.
Although each part of the compound subject is singular (ranger and camper), taken together (joined by and), each one becomes a part of a plural structure and, therefore, must take aplural verb (see) to agree in the sentence.
SUBJECT-VERB RULE #1 – Two or more singular (or plural) subjects joined by and act as a plural compound subject and take a plural verb (singular + singular = plural).
You can check the verb by substituting the pronoun they for the compound subject.
Or and nor as joiners work somewhat differently from and. While the word and seems to ADD things together, or and nor do not. They suggest a CHOICE.
This sentence makes use of a compound subject (two subject nouns joined together by or). Each part of the compound subject (ranger, camper) is singular. Even though both words function together as subject (joined by or), the subject still remains SINGULAR (ranger or camper) since a CHOICE is implied.
This compound subject, therefore, requires a singular verb to agree with it.
SUBJECT-VERB RULE #2 – Two or more SINGULAR subjects joined by or (or nor) act as a singular compound subject and, therefore, take a singular verb to agree.
This compound subject, therefore, requires a singular verb to agree with it.
SUBJECT-VERB RULE #2 – Two or more SINGULAR subjects joined by or (or nor) act as a singular compound subject and, therefore, take a singular verb to agree.
Note: Two or more plural subjects joined by or (or nor) would naturally take a plural verb to agree.
If the individual parts of the compound subject are joined by and, always use a plural verb.
2. If the individual parts of the compound subject are joined by or or nor, use the verb form (singular or plural) which will agree with the subject closer to the verb.
source: http://www.towson.edu/ows/moduleSVAGR.htm