Subordinating conjunctions: what they do and how they differ from coordinating conjunctions
On-ramps allow traffic from subsidiary roads – like Burke Road – to join major freeways – like the Eastern Freeway
In my post on coordinating conjunctions, I explained how that group of conjunctions joins shorter sentences together in a way that balances the two original sentences, leaving them of equal importance in the new sentence.
Subordinating conjunctions also join shorter sentences into longer sentences but they do so in a different way: subordinating conjunctions make one part of the new sentence less important than the other. Subordinating conjunctions make the sentence (or clause) that they introduce subordinate to the main clause they connect to. This is why I think subordinating conjunctions are like freeway on-ramps, which join a less important road to the major freeway.
Consider these sentences (the subordinating conjunctions are in bold):
- Susan was shopping for last-minute presents, while Tim made a special Christmas Eve dinner.
- She was late home, because she was caught in heavy traffic.
- Although she had wanted to be on time, a car accident had caused the traffic to bank up.
- The salmon was not spoilt, since Tim did not put it in the oven until she arrived home.
The clause (short sentence) that follows each subordinating conjunction adds extra information to the main clause (the other part of the sentence), but the use of the subordinating conjunctions makes this information less important. Contrast the same sentences using coordinating conjunctions:
- Susan was shopping for last-minute presents and Tim made a special Christmas Eve dinner.
- She was caught in heavy traffic and she was late home.
- She had wanted to be on time but a car accident had caused the traffic to bank up.
- Tim did not put the salmon in the oven until she arrived home and it was not spoilt.
- Tim did not put the salmon in the oven until she arrived home so it was not spoilt.
In the versions with the coordinating conjunctions, neither part of the sentence is more important than the other. (The exception here is the last example, using so. My opinion, as someone who tends to prefer traditional grammar, is that so is actually a subordinating conjunction, and this sentence is like the previous group of examples, but followers of modern grammar disagree; they would argue that the last example is the same as the other ones in this second group. You can make up your own minds.)
When we use subordinating conjunctions to join two or more short sentences, the new longer sentence is called a complex sentence. A complex sentence is made up of a main clause (without a subordinating conjunction to start it), and one or more subordinate clauses that each start with a subordinating conjunction. Just to make the jargon more confusing, main clauses are also called principal clauses and subordinate clauses are also called dependent clauses.
While there are only three (or seven) coordinating conjunctions, depending on how you define them, there are many more subordinating conjunctions, and they can even be made up of more than one word. Here are some of the most common subordinating conjunctions:
after, although, as, as if, as soon as, because, before, if, in case, in order that, since, than, unless, until, when, whether, while
Subordinating clauses must join to a main clause
A subordinating conjunction that doesn’t link to a main clause is like an unconnected on-ramp
People used to think that coordinating conjunctions could not be used in a sentence that was made up of only one clause: that the coordinating conjunction had to join two clauses. But you can start a sentence made up of just one clause with a coordinating conjunction (like this one).
What you cannot do is have a single-clause sentence starting with a subordinating conjunction.
Let me put this another way: a subordinating conjunction must join the clause that follows it to another clause.
Consider these examples:
- While Tim made a special Christmas Eve dinner.
- Because she was caught in heavy traffic.
- Although she had wanted to be on time.
- Since Tim did not put it in the oven.
- Until she arrived home.
These subordinate clauses (single sentences or clauses following a subordinating conjunction) do not make sense on their own. We are left hanging, like a disconnected freeway ramp; we need another clause in order for the sentence to make sense. They depend on another clause for their full meaning.
What about ‘because’?
- Why was Susan late? Because she was caught in heavy traffic.
The answer to the question in this example looks like an example of a subordinating clause that makes sense on its own. But it actually doesn’t: it depends on the previous sentence (the question) for its meaning. When we are speaking, we often give answer a question with just a subordinate clause, because this saves time. To answer the question Why was Susan late? with a grammatically correct sentence, we would write Susan was late, because she was caught in heavy traffic or Since Susan was caught in heavy traffic, she was late. I say ‘write’, because we do not speak in grammatical sentences: grammar is for writing, not for conversation.
Commas and subordinating conjunctions
Subordinate clauses, unless they are very short, are usually separated from the main clause by commas. If the subordinate clause comes first, the comma is at the end of the subordinate clause. The comma is placed before the subordinating conjunction, when the subordinate clause comes after the main clause. If the subordinate clause is in the middle of the sentence, it will have commas at its start and finish.
- If the subordinate clause comes first, the comma is at the end of the subordinate clause. (Subordinate clause is first, with the comma at its end)
- The comma is placed before the subordinating conjunction, when the subordinate clause comes after the main clause. (Subordinate clause is second, with comma before it)
- Subordinate clauses, unless they are very short, are usually separated from the main clause by commas. (Subordinate clause is in the the middle, with commas before and after it)
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