Complex Sentences
These, you will not be surprised to learn, are more complicated than simple sentences. They contain additional information in the form of subordinate clauses. If we take our first sentence about Granny and add a conjunction (or joining word) to it, we see that it becomes incomplete:
Although Granny put the Christmas present on the table …
It has moved from a simple sentence to an unfinished fragment and needs further information to make it complete. Let’s add some more details and have another look:
Although Granny put the Christmas present on the table, she had forgotten to wrap it.
That now makes sense as a complete, complex sentence. Our initial sentence (‘Granny put the present on the table’) has become a subordinate clause and our additional information a main clause. The two are joined together by the conjunction although.
Subordinating conjunctions join subordinate clauses to main clauses. Examples include unless, since, whereas, while, if and after.
Compound Sentences
Complex sentences, as we have seen, contain a subordinating (or dependent) clause that will not stand up on its own, and a main (or independent) clause that will. In compound sentences, however, we have clauses of equal weight, all of them independent (that is to say making sense on their own), joined by a conjunction, usually and, but or or. An example of this is:
I’ll take the high road, but you’ll take the low road.
Because the two parts are independent, this could just as well be written in two complete simple sentences:
I’ll take the high road. You’ll take the low road.