Conjunctions connect grammatical structures. We have two – or really 2.5 – types of conjunctions. (2.5 because the conjunctive adverb is a kind of half-and-half case: half conjunction, half adverb.)
Kinds of conjunctions:
· Conjunctive adverb
Coordinating conjunctions are a small group of words: and, but, or; yet, nor, for, so.
They coordinate, in that they join grammatical structures of equal forms together. So noun phrases with noun phrases, verb phrases with verb phrases, clause with clause, and so on.
Elvis and Ivy went to the play.
Elvis went to the play, but Ivy stayed home.
In the first sentence, and joins two noun phrases – Elvis, Ivy.
In the second but joins two clauses. (When that happens, we have a compound sentence.)
Sometimes coordinating conjunctions work in pairs. When they do this, they’re called correlative conjunctions.
Both Elvis and Ivy went to the play.
Neither the fish nor the pigs can fly.
Subordinating conjunctions, on the other hand, connect grammatical structures that are not equal. One structure will be subordinated to the other – specifically, it will be modifying the other, or main, clause.
Subordinating conjunctions are words like so that, if, when, since, although – a longer list is on page 145 in your text.
Luis drove so that Polly and Davis could sleep.
After we finished dinner, we went to a movie.
Notice the different functions of the word that in the two sentences – in the first sentence, it is a part of a subordinating conjunction; in the second, it is a determiner. And notice that after, which can be a preposition, is here a subordinating conjunction.
Nearly all subordinated clauses function adverbially.
I’ll wash the dishes if you take out recycling.
Polly got up at dawn so that she could study before class.
Before Orin got sick, he ran six miles a day.
Finally, we have the conjunctive adverbs. These are dual purpose tool – they connect like conjunctions, but modify like adverbs. They are words like however, besides, also, therefore, for example, meanwhile, and so on. (See page 142 in your text for a longer list.)
Elvis went to bed early; however, he forgot to set the alarm.
Stir in the sugar; then fold in the eggs.
Conjunctive adverbs are different from subordinating conjunctions in two ways. First, conjunctive adverbs connect independent clauses. This means that the clauses they connect could stand alone, as complete sentence.
Elvis went to bed early. However, he forgot to set the alarm.
Stir in the sugar. Then fold in the eggs.
That is not true of subordinating conjunctions, since in that construction one of the clauses being connected is always subordinated to the other – specifically, as we noted before, one clause is modifying some aspect of the other clause.
Luis drove. So that Polly and Davis could sleep.
After we finished dinner. We went to a movie.
Also, with conjunctive adverbs, the conjunctive adverb can frequently be moved around in the sentence. This is never true of a subordinating conjunction.
Elvis went to bed early; he forgot, however, to set the alarm.
Elvis went to bed early; he forgot to set the alarm, however.
So that Luis drove Polly and Davis could sleep.
We finished after dinner, we went to a movie.
We finished dinner, after we went to a movie.
(Note that both of these last two make a kind of sense, but they aren’t providing the same meaning as the original sentence)
Usage: Sentences that are or should be linked with some sort of conjunction often create the sentence error called, variously, a run on sentence, a comma splice, a comma fault, or fused sentence.
The rule to remember is that if you have two clauses that could be independent clauses – that could be complete sentences, in other words – they need some sort of punctuation (besides a comma) or some sort of conjunction between them. If your conjunction is a conjunctive adverb, they still need punctuation between them.
Lily was late for work, she couldn’t find her keys.
The movie starts in an hour, I can’t wait.
I need college algebra to graduate, I suck at math.
All these are run-on sentences. They can be fixed in various ways – by putting semi-colons or periods in place of the commas, or by using conjunctions, or a combination of these.
Lily was late for work, and she couldn’t find her keys.
Lily was late for work; also she couldn’t find her keys.
The movie starts in an hour; I can’t wait.
I need college algebra to graduate, even though I suck at math.