Super Glue Words (2)

Take out your list of Glue Words.

Notice that the following words are all marked with an asterisk (*):

for
but
until
till
since
before
as
after
until

These words have a superpower: they can change their function, depending on their place within a sentence.

Consider the fanboy, "but".

"But" is a coordinating conjunction; however, in some sentences, it might actually be a preposition.

I like all the boys but him.	In this sentence, "but" is a preposition.
I like all the boys, but I don't like him.	In this sentence, "but" is a coordinating conjunction (fanboy).

How can you tell the difference?

Prepositions are always followed by a noun (or noun phrase).
Conjunctions are always followed by a complete clause.

"For" is another such word. When used as an old-fashioned word for "because", it functions as a fanboy (coordinating conjunction). But more commonly, it's just a preposition.

I studied Japanese for many years.

"Many years" is a noun phrase, so "for" is a preposition.

I love to watch Anna, for she dances beautifully.

"She dances beautifully" is a complete clause, so "for" is a conjunction.

Specifically, it's a coordinating conjunction (fanboy).

There are only two fanboys that can morph into prepositions:

In addition, a handful of subordinating conjunctions have this superpower:

after
as
before
since
till / until

To determine the function of these words within a sentence, examine the words that follow them.

I went to the park after school.	"School" is a noun; therefore,"after" is a preposition.
I got dressed, after I took a shower.	"I took a shower" is a clause; therefore, "after" is a subordinating conjunction.

He works as a waiter.	preposition
He called my name as I walked by.	subordinating conjunction

I ate a candy bar before lunch.	preposition
I ate a candy bar before I ate lunch.	subordinating conjunction

I haven't eaten since yesterday.	preposition
I haven't seen him since we went to the beach.	subordinating conjunction

You will have to wait till tomorrow.	preposition
I won't be happy till you come back.	subordinating conjunction

The pond stays frozen until March.	preposition
I stayed until he arrived.	subordinating conjunction

Related:

Don’t confuse because, which is a subordinating conjunction, with because of, which is a preposition.

She got the job because of her experience.

Preposition

We stopped for lunch because I was hungry.

subordinating conjunction

Instructions for the Quiz

Identify the underlined word.

preposition
coordinating conjunction
subordinating conjunction

Quiz