Prepositions and conjunctions, both are very essential parts
of speech. It is quite easy to understand if they are learnt independently. But
in certain cases, the user is not able to make out whether a given word has
been used as a preposition or a conjunction. So, it becomes very significant to
ascertain the proper use of a given part of speech. The topic in hand intends
to discuss and find out a few words which generally appear as preposition on
their faces, but they can be very much used as conjunctions, and vice-versa. Examples
of such prepositions and conjunctions that are used interchangeably are: till,
until, before, after, but, for, since and without etc.
Before going into further details, let us once again recollect
what exactly prepositions and conjunctions are.
Prepositions are generally short words that have a noun or a
pronoun after them as their objects. For a word to function as a preposition, it
must be followed by a noun or an equivalent expression (along with qualifiers).
On the other hand, conjunctions join similar kinds of parts of
speech or constructions. For example, a conjunction joins a noun / pronoun with
another noun / pronoun, an adjective with another adjective, an adverb with
another adverb and a phrase with another phrase and a clause with another clause.
As far as utility is concerned, conjunctions are more versatile than
In order to find out whether a given word has been used as a
preposition or conjunction, the word or group of words that follow the word to
be tested must be closely looked at. If a word that looks like a preposition
and is followed by a clause, it is invariably a conjunction. On the other hand,
if the word is followed directly by a noun or a pronoun, it is a preposition
(this noun / pronoun must not function as subject of the verb / clause that
Let us look at a few examples in order to clarify the topic
brought all the books but one.
brought all the books but I forgot to bring one.
We went for
a walk after dinner.
We went for
a walk after we had taken a dinner.
Tom stood in
the line before me.
completed his task before going out of the house.
home before it began to rain.
for a few minutes for me.
hard for you have very less time.
She went out
without taking her purse with her.
She went out
without her purse.
here as a teacher.
hurry up as we have to catch the early train.
shall continue till 4:00 p.m.
shall continue till it is 4:00 p.m.
You have to
wait until sunrise.
You have to wait until the sun rises.
In the above examples, pay attention to the words in bold
letters (both underlined as well as not underlined). On careful observation, it can be easily made
out that the words in bold letters and not underlined, are followed directly
by a noun or a pronoun. These words in bold letters are prepositions,
where the nouns and pronouns placed after them serve as objects of respective
On the other hand, the underlined words in bold
letters are followed by clauses or phrases that invariably contain a
verb, and join these phrases and clauses with remaining part of the sentence.
Since they join similar parts, the underlined words in bold letters
The presence of a verb (in any form except the
gerundial infinitive) after a word that looks like a preposition is
sufficient proof to assert that the word under consideration is not a