Introduction

We’ve covered the majority of parts of speech: nouns, pronouns, verbs, adjectives, and adverbs. So, what’s left?

What remains are the little connecting word categories: conjunctions, prepositions, and articles. These small words may not seem as important as verbs, nouns, and adjectives, but they are the backbone of English: these are the words that give our language structure.

Conjunctions

Conjunctions are the words that join sentences, phrases, and other words together. Conjunctions are divided into several categories, all of which follow different rules. We will discuss coordinating conjunctions, adverbial conjunctions, and correlative conjunctions.

Coordinating Conjunctions

The most common conjunctions are and, or, and but. These are all coordinating conjunctions. Coordinating conjunctions are conjunctions that join, or coordinate, two or more equivalent items (such as words, phrases, or sentences). The mnemonic acronym FANBOYS can be used to remember the most common coordinating conjunctions: for, and, nor, but, or, yet, and so.

• For: presents a reason (“They do not gamble or smoke, for they are ascetics.”)
• And: presents non-contrasting items or ideas (“They gamble, and they smoke.”)
• Nor: presents a non-contrasting negative idea (“They do not gamble, nor do they smoke.”)
• But: presents a contrast or exception (“They gamble, but they don’t smoke.”)
• Or: presents an alternative item or idea (“Every day they gamble, or they smoke.”)
• Yet: presents a contrast or exception (“They gamble, yet they don’t smoke.”)
• So: presents a consequence (“He gambled well last night, so he smoked a cigar to celebrate.”)

Here are some examples of these used in sentences:

• Nuclear-powered artificial hearts proved to be complicated, bulky, and expensive.
• In the 1960s, artificial heart devices did not fit well and tended to obstruct the flow of venous blood into the right atrium.
• The blood vessels leading to the device tended to kink, obstructing the filling of the chambers and resulting in inadequate output.
• Any external injury or internal injury put patients at risk of uncontrolled bleeding because the small clots that formed throughout the circulatory system used up so much of the clotting factor.
• The current from the storage batteries can power lights, but the current for appliances must be modified within an inverter.

As you can see from the examples above, a comma only appears before these conjunctions sometimes. So how can you tell if you need a comma or not? There are three general rules to help you decide.

Rule 1: Joining Two Complete Ideas

Let’s look back at one of our example sentences:

The current from the storage batteries can power lights, but the current for appliances must be modified within an inverter.

There are two complete ideas in this sentence. A complete idea has both a subject (a noun or pronoun) and a verb. The subjects have been italicized, and the verbs bolded:

• the current from the storage batteries can power lights
• the current for appliances must be modified within an inverter.

Because each of these ideas could stand alone as a sentence, the coordinating conjunction that joins them must be preceded by a comma. Otherwise you’ll have a run-on sentence.

Rule 2: Joining Two Similar Items

So what if there’s only one complete idea, but two subjects or two verbs?

• Any external injury or internal injury put patients at risk of uncontrolled bleeding because the small clots that formed throughout the circulatory system used up so much of the clotting factor.
• In the 1960s, artificial heart devices did not fit well and tended to obstruct the flow of venous blood into the right atrium.

The first sentence has two subjects: external injury and internal injury. The second sentence has two verbs: did not fit well and tended to obstruct. In each sentence, the two similar items are separated from each other by a conjunction, but no comma is required.

Rule 3: Joining Three or More Similar Items

So what do you do if there are three or more items?

• Anna loves to run, David loves to hike, and Luz loves to dance.
• Fishing, hunting, and gathering were once the only ways for people do get food.
• Emanuel has a very careful schedule planned for tomorrow. He needs to work, study, exercise, eat, and clean.

As you can see in the examples above, there is a comma after each item, including the item just prior to the conjunction. There is a little bit of contention about this, but overall, most styles prefer to keep the additional comma (also called the serial comma). We discuss the serial comma in more depth in Text: Commas.

Adverbial Conjunctions

Adverbial conjunctions link two separate thoughts or sentences. When used to separate thoughts, as in the example below, a comma is required on either side of the conjunction.

The first artificial hearts were made of smooth silicone rubber, which apparently caused excessive clotting and, therefore, uncontrolled bleeding.

When used to separate sentences, as in the examples below, a semicolon is required before the conjunction and a comma after.

• The Kedeco produces 1200 watts in 17 mph winds using a 16-foot rotor; on the other hand, the Dunlite produces 2000 watts in 25 mph winds.
• For short periods, the fibers were beneficial; however, the eventual buildup of fibrin on the inner surface of the device would impair its function.
• The atria of the heart contribute a negligible amount of energy; in fact, the total power output of the heart is only about 2.5 watts.

Adverbial conjunctions include the following words; however, it is important to note that this is by no means a complete list.

Correlative Conjunctions

Correlative conjunctions are word pairs that work together to join words and groups of words of equal weight in a sentence. This video will define this types of conjunction before it goes through five of the most common correlative conjunctions:

The table below shows some examples of correlative conjunctions being used in a sentence:

Prepositions

Prepositions are relation words; they can indicate location, time, or other more abstract relationships. Prepositions are noted in bold in these examples:

• The woods behind my house are super creepy at night.
• She sang until three in the morning.
• He was happy for them.

A preposition combines with another word (usually a noun or pronoun) called the complement. Prepositions are still in bold, and their complements are in italics:

• The woods behind my house are super creepy at night.
• She sang until three in the morning.
• He was happy for them.

Prepositions generally come before their complements (e.g., in England, under the table, of Jane). However, there are a small handful of exceptions, including notwithstanding and ago:

• Financial limitations notwithstanding, Phil paid back his debts.
• He was released three days ago.

Prepositions of location are pretty easily defined (near, far, over, under, etc.), and prepositions about time are as well (before, after, at, during, etc.). Prepositions of “more abstract relationships,” however, are a little more nebulous in their definition. The video below gives a good overview of this category of prepositions:

So far, all of the prepositions we’ve looked at have been one word (and most of them have been one syllable). The most common prepositions are one-syllable words. According to one ranking, the most common English prepositions are on, in, to, by, for, with, at, of, from, as.

There are also some prepositions that have more than one word:

• in spite of (She made it to work in spite of the terrible traffic.)
• by means of (He traveled by means of boat.)
• except for (Joan invited everyone to her party except for Ben.)
• next to (Go ahead and sit down next to Jean-Claude.)

Prepositions in Sentences

You’ll often hear about prepositional phrases. A prepositional phrase includes a preposition and its complement (e.g., “behind the house” or “a long time ago“).

Articles

There are three articles in the English language: the, a, and an. These are divided into two types of articles: definite (the) and indefinite (a, an). The definite article indicates a level of specificity that the indefinite does not. “An apple” could refer to any apple; however “the apple” is referring back to a specific apple.

Thus, when using the definite article, the speaker assumes the listener knows the identity of the noun’s referent (because it is obvious, because it is common knowledge, or because it was mentioned in the same sentence or an earlier sentence). Use of an indefinite article implies that the speaker assumes the listener does not have to be told the identity of the referent.

There are also cases where no article is required:

• with generic nouns (plural or uncountable): cars have accelerators, happiness is contagious, referring to cars in general and happiness in general (compare the happiness I felt yesterday, specifying particular happiness);
• with many proper names: Sabrina, France, London, etc.

Watch this quick introduction to indefinite and definite articles and the difference between the two:

Indefinite Article

The indefinite article of English takes the two forms a and an. These can be regarded as meaning “one,” usually without emphasis.

Distinction between a and an

You’ve probably learned the rule that an comes before a vowel, and that a comes before a consonant. While this is generally true, it’s more accurate to say that an comes before a vowel sound, and a comes before a consonant sound. Let’s look at a couple of examples with a:

• a box
• a HEPA filter (HEPA is pronounced as a word rather than as letters)
• a one-armed bandit (pronounced “won. . . “)
• a unicorn (pronounced “yoo. . . “)

Let’s try it again with an:

• an apple
• an EPA policy (the letter E read as a letter still starts with a vowel sound)
• an SSO (pronounced “es-es-oh”)
• an hour (the h is silent)
• an heir (pronounced “air”)

Definite Article

The definite article the is used when the referent of the noun phrase is assumed to be unique or known from the context. For example, in the sentence “The boy with glasses was looking at the moon,” it is assumed that in the context the reference can only be to one boy and one moon.

The can be used with both singular and plural nouns, with nouns of any gender, and with nouns that start with any letter. This is different from many other languages which have different articles for different genders or numbers. The is the most commonly used word in the English language.

Word Order

In most cases, the article is the first word of its noun phrase, preceding all other adjectives and modifiers.

The little old red bag held a very big surprise.

There are a few exceptions, however:

• Certain determiners, such as all, both, half, double, precede the definite article when used in combination (all the team, both the girls, half the time, double the amount).
• Such and what precede the indefinite article (such an idiot, what a day!).
• Adjectives qualified by too, so, as and how generally precede the indefinite article: too great a loss, so hard a problem, as delicious an apple as I have ever tasted, I know how pretty a girl she is.
• When adjectives are qualified by quite (particularly when it means “fairly”), the word quite (but not the adjective itself) often precedes the indefinite article: quite a long letter.

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