Subject-Verb Agreement

Tips from Proofreading: Plain and Simple by Debra Hart May, with my own commentary:

• "Singular subjects joined by and become plural."
• A good test for this is to try to replace the subjects with one word. For example, in the sentence, "Jane and Nicole loves shopping," you can replace the two subjects with "they." This makes the sentence "They loves shopping," which is incorrect. If you replace "loves" with the singular verb "love," it becomes "They love shopping," which is correct. This means that the correct verb for the sentence must be "love," and the original sentence should be "Jane and Nicole love shopping."
• A good test for this is to try to replace the subjects with one word. For example, in the sentence "Jane and I went shopping," you can replace the two subjects with "we," making it "We went shopping." The verb tense agrees with the subject, so it is correct.
• "Singular subjects joined by or stay singular."
• In this case, try getting rid of one subject to see if it sounds right. In the sentence "Sylvia or Tom go to the market," if you take away one subject and the connecting word, you get "Tom go to the market," which is incorrect. Instead, replace "go" with "goes," making it "Tom goes to the market." This subject-verb combination is correct, so therefore "goes" should be used in the original sentence, "Sylvia or Tom goes to the market."
• "A combination of singular and plural subjects joined by or can be either singular or plural, depending on whichever occurs closer to the verb."
• For this type of sentence, you have to ignore the first subject in order to determine the proper verb form. In the sentence, "The band members and Jack order dinner," you would ignore "The band members" and read the sentence as "Jack order dinner." This verb does not agree with the subject, so the verb must be "orders." Putting this back in the original sentence, it becomes "The band members and Jack orders dinner."
• "Singular collective nouns (group, team) are singular."
• In this case, it is pretty straightforward. In a sentence such as "The baseball team shovel snow," the collective noun is singular, so therefore the verb should follow suite. This would make the sentence "The baseball team shovels snow." If it helps, try replacing the noun (the baseball team) with a singular pronoun, such as "he." This would make the original sentence "He shovel snow," which is incorrect, so the second option must be true. "He shovels snow" is much better.
• "Everyone, everybody, and each (when used as a pronoun) are singular."
• Take, for example,the sentence "Everybody runs in a circle." If you replace the pronoun with another singular pronoun, such as "she," the sentence becomes "She runs in a circle." Because the subject and verb agree, this must be correct, confirming that the original sentence works.
• "Prepositional phrases often end up between subjects and their verbs. Take care that you don't let them confuse the subject-verb match-up."
• In the sentence "Each of the members come up with unique projects." the prepositional phrase is "of the members." After you identify this phrase, you can eliminate it from the sentence, making it "Each come up with unique projects." If you apply the technique for the rule we just discussed, it becomes "He come up with unique projects." Adjusting the verb into the correct form, the sentence is changed into "He comes up with unique projects." Applying this to the original sentence makes it into "Each of the members comes up with unique projects."

I know this sounds like a lot of steps, but it all happens very fast in your mind. Once you learn these easy-to-follow rules, it becomes second nature when you are writing. Just keep working on it and soon enough, you won't have to think about it at all!