Conjunctions

Definition: a word that connects or joins parts of a sentence.

Coordinating Conjunctions, commonly referred to as FANBOYS

and, but, or, yet, for, nor, so

The comma is always correct when used to separate two independent clauses connected by a coordinating conjunction. A comma is also correct when and is used to attach the last item of a serial list, although it is common to omit the final comma:

Brad spent his summer studying basic math, writing, and reading comprehension.

When a coordinating conjunction is used to connect all the elements in a series, a comma is not used:

Presbyterians and Methodists and Baptists are the prevalent Protestant congregations in Oklahoma.

A comma is also used with but when expressing a contrast:

This is a useful rule, but difficult to remember.

In most of their other roles as joining ideas together (other than joining independent clauses), coordinating conjunctions can join two sentences elements without a comma.

Hemingway and Fitzgerald are among the American expatriates of the between-the-wars era.
Hemingway was renowned for his clear style and his insights into American notions of male identity.

Beginning a Sentence with And or But

A frequently asked question is whether and or but can be used at the beginning of a sentence. A sentence beginning with and, because or but will tend to draw attention to itself and its transitional function. Writers should examine such sentences with three things in mind: (1) does it create a sentence fragment? (2) would the sentence function just as well without the initial conjunction? (3) should the sentence be connected to the previous sentence?

The Case of Then and Than

Than is used to make comparisons. Consider the following sentence:

Piggy would rather be rescued then stay on the island

It uses the wrong word because a comparison needs to be made between Piggy's two choices; something that requires than. In the sentence, "Other than Pincher Martin, Golding did not write another popular novel," the adverbial construction "other than" helps us make an implied comparison; this usage is perfectly acceptable in the United States but careful writers in the UK try to avoid it (Burchfield).

Generally, the only question about than arises when we have to decide whether the word is being used as a conjunction or as a preposition. If it's a preposition, then the word that follows it should be in the object form.

He's taller and somewhat more handsome than me.
Just because you look like him doesn't mean you can play better than him.

Most careful writers will insist that than be used as a conjunction; it's as if part of the clause introduced by than has been left out:

He's taller and somewhat more handsome than I [am handsome].
You can play better than he [can play].

In formal text, something that applies to exams such as the TOEFL, you should use than as a conjunction and follow it with the subject form of a pronoun (where a pronoun is appropriate). Then is a conjunction, but it is not one of the little conjunctions listed at the top of this page. We can use the FANBOYS conjunctions to connect two independent clauses; usually, they will be accompanied (preceded) by a comma. Too many students think that then works the same way:

Caesar invaded Gaul, then he turned his attention to England.

You can tell the difference between then and a coordinating conjunction by trying to move the word around in the sentence. We can write

he then turned his attention to England;

he turned his attention, then, to England;

he turned his attention to England then.

 

The word can move around within the clause. Try to move a conjunction, and you will quickly see that it cannot move around.

Caesar invaded Gaul, and then he turned his attention to England.

 

The word and is stuck exactly there and cannot move like then, which is more like an adverbial conjunction than a coordinating conjunction. Our original sentence in this paragraph

Caesar invaded Gaul, then he turned his attention to England

is a comma splice, a faulty sentence construction in which a comma tries to hold together two independent clauses all by itself:

the comma needs a coordinating conjunction to help out, and the word then simply doesn't work that way.

Subordinating Conjunctions

A subordinating conjunction comes at the beginning of a dependent clause and establishes the relationship between the dependent clause and the rest of the sentence. It also turns the clause into something that depends on the rest of the sentence for its meaning.

He took to the stage as though he had been preparing for this moment all his life.
Because he loved acting, he refused to give up his dream of being in the movies.
Unless we act now, all is lost.

Notice that some of the subordinating conjunctions in the table below — after, before, since — are also prepositions, but as subordinating conjunctions they are being used to introduce a clause and to subordinate the following clause to the independent element in the sentence.

Common Subordinating Conjunctions

after, although, as, as if, as long as, as though, because, before, even if, even though, if, if only, in order that, now that, once, rather than, since, so that, than, that, though, till, unless, until, when, whenever, where, whereas, wherever, while
 

The Case of Like and As

Strictly speaking, the word like is a preposition, not a conjunction. It can, therefore, be used to introduce a prepositional phrase ("My brother is tall like my father"), but it should not be used to introduce a clause ("My brother can't play the piano like as he did before the accident" or "It looks like as if basketball is quickly overtaking baseball as America's national sport."). To introduce a clause, it's a good idea to use as, as though, or as if, instead.

Like As I told you earlier, the lecture has been postponed.
It looks like as if it's going to snow this afternoon.
Johnson kept looking out the window like as though he had someone waiting for him.

In formal writing, it's a good idea to use like for situations in which similarities are being pointed out:

This community college is like a two-year liberal arts college.
However, when you are listing things that have similarities, such as is probably more suitable:
The college has several highly regarded neighbors, like such as the Mark Twain House, St. Francis Hospital, the Connecticut Historical Society, and the UConn Law School.
 

Omitting That

The word that is used as a conjunction to connect a subordinate clause to a preceding verb. In the following sentences, we can happily omit the that (or keep it, depending on how the sentence sounds to us):

Isabel knew [that] she was about to be fired.
She definitely felt [that] her fellow employees hadn't supported her.
I hope [that] she doesn't blame me.

Sometimes omitting the that creates a break in the flow of a sentence, a break that can be adequately bridged with the use of a comma:

The problem is, that production in her department has dropped.
Remember, that we didn't have these problems before she started working here.

Beginning a Sentence with Because

Somehow, the idea that people should not begin a sentence with because has become a common rule. This is largely because using it may cause a sentence to become a fragment if people are not careful.

Because e-mail now plays such a huge role in our communications industry.

When the "because clause" is properly connected to another idea, there is absolutely nothing wrong with it:

Because e-mail now plays such a huge role in our communications industry, the postal service would very much like to see it taxed in some manner.

Correlative Conjunctions

Some conjunctions combine with other words to form what are called correlative conjunctions. They always travel in pairs, joining various sentence elements that should be treated as grammatically equal.

She led the team not only in statistics but also by virtue of her enthusiasm.
Polonius said, "Neither a borrower nor a lender be."
Whether you win this race or lose it doesn't matter as long as you do your best.

Here is a brief list of common correlative conjunctions.

both . . . and
not only . . . but also
not . . . but
either . . . or
neither . . . nor
whether . . . or
as . . . as