Subordinators often draw from the same list of words as prepositions, so it’s important that you understand the difference between a subordinate clause and a prepositional phrase. In short, a subordinator precedes an entire clause, and a preposition precedes a nominal only.
Be careful with the following Prepositions and Subordinators:
During is a preposition. It cannot be used as a subordinator
During I was a child, I lived in Denmark. (Wrong)
During my childhood, I lived in Denmark. (Right)
While I was a child, I lived in Denmark. (Right)
In spite of/Despite are prepositions. They cannot be used as subordinators.
In spite of I was very young, I still got the job. (Wrong)
In spite of my youth, I still got the job. (Right)
Although I was very young, I still got the job. (Right)
Before, After, and Until can be used as either prepositions or subordinators.
Do not go outside after it is dark.
Do not go outside after dark.
I worked until 9:00 this evening.
I worked until my replacement showed up.
For and Since have many uses.
For as a coordinating conjunction.
I cannot tell a lie, for that would be dishonest. (for means because)
For in phrases of duration
He lived in New Jersey for five years.
For to indicate “on behalf of”
He fixed the TV for his daughter.
For to indicate intended recipient
I bought this for you.
For to indicate occasion
I bought this for Christmas.
For to indicate cost
I bought this for $399.
For to indicate purpose
I bought this for fun.
Since to indicate duration
I have been in Toledo since last Tuesday. (preposition)
I have been in Toledo since I was a child. (subordinator)
Since to indicate reason
Since I have nothing else to do, I will attend your party.
Yet can be used as a conjunction or an adverb.
She hasn’t arrived yet.
He worked hard, yet he wasn’t able to complete the job on time.