Subject Verb Agreement
Even if you've got your basic subject-verb agreement rules down pat, you should know that English is never quite that easy. There are many exceptions just waiting to confuse you. We'll explore a few of them here.
Group Nouns
Take group nouns. Group nouns, or collective nouns (as they're sometimes called), refer to groups of things but are typically themselves singular. This includes words like team, party, or crew - any singular noun that encompasses a group of people or things.
In general, since these group nouns have their own plural forms - you can have a team (singular) or teams(plural) - you should use a singular verb with the singular form of the noun. Don't let the fact that the word contains multiple things confuse you. For example, The party IS getting started at 9 o'clock (that's one single unit of partying). Or if you wanted to make it plural you could say The parties are going on downtown because you're referring to more than one party. In any case, keep in mind that just because a word refers to or contains a number of things doesn't make it plural.
We're not quite finished yet, however. Some group nouns can be either singular or plural depending on the context. For example, in this sentence - The gang are going their separate ways - you use a plural verb ('are') because the sentence is referring to the individual gang members, not the gang as one collective whole. If you were referring to the gang as a collective whole, then you would use a singular verb, as in The gang is going to a big gang meet-up and dance tonight. More often than not, the group nouns will take a singular verb because they're being used to talk about a collective unit, but you need to be aware of the rare cases when they call for a plural verb - when there is discord between the members that make up the unit.
Stealth Singular Nouns
Another type of tricky noun is what I like to call the 'stealth singular noun.' These noun-ninjas look like plural nouns (they have a plural form - either an 's' or 'es' on the end of the word), but they refer to a single thing and thus they demand a singular form of a verb to match up with. Some examples of these stealth singular nouns include politics, gymnastics, mathematics, news, and darts, as well as certain food words when you're referring to a single dish (like eggs benedict).
Some of these are easy to hear because of everyday usage. For instance, you would never say The news are on; you would say The news is on because you know that news refers to a single entity. But with a word like politics, it's a little trickier. Politics seems to contain a lot of different thoughts, ideas, opinions, and disciplines, so it's tempting to say Politics are usually boring, for instance. But 'politics' refers to a single discipline, and so it must be treated as singular. The same goes for other nouns ending in ics. So a proper sentence would read: Politics is boring but mathematics is worse; still, gymnastics is pretty great.If you think that a plural-sounding noun might actually be singular, ask yourself: Can it be treated as a single entity? If it can, then it's probably a singular noun and therefore requires a singular verb.
Indefinite Pronouns
Like our 'stealth' singular nouns, many indefinite pronouns look like they should be plural but refer to only a singular subject and therefore require a singular verb form. These include the pronouns each, everyone, everybody, anyone, nobody, no one, nothing, everything, anybody, anyone, anything, someone, something, somebody, either, neither, other, and one.
In other words, you would say Everybody is going to the parade, not Everybody are going to the parade, or Someone leaves notes for me in my locker every morning, not Someone leave notes for me in my locker every morning. Why singular? Because while these indefinite pronouns may seem to refer to groups, they actually refer to individual actors - some (one) body or every (one) body or every (individual) thing.
I hope you don't find that too confusing, but if you do, you can always memorize these indefinite pronouns and remember that they call for a singular verb. You'll get the hang of it in no time.