Introduction to Preposition

A. A preposition is a word like in, to, or for. It can also be more than one word: out of, in front of. A preposition usually comes before a noun phrase.

into the building      at two o'clock       without a coat

Some prepositions can also come before an adverb.

until tomorrow       through there

B. A phrase like on my desk or at the office is called a prepositional phrase. A prepositional phrase often functions as an adverbial.

Everything was quiet at the office.

A prepositional phrase can sometimes come after a noun.

The panic at the office meant that I got home late.

There are many idiomatic combination where a particular preposition follows a verb, adjective, or noun.

wait for a bus      afraid of the dark     an interest in music

C. We can use certain prepositions before a gerund.

We succeeded in reaching an agreement. 

But an infinitive cannot be the object of a preposition.

NOT We succeeded in to reach an agreement.

We cannot use a preposition before a that-clause.

NOT We're hoping for that it stays fine.

We use one of these patterns.

We're hoping for fine weather.           We're hoping (that) it stays fine.

But we can use a preposition before a wh-clause.

I'd better make a list of what we need.

D. We can modify a preposition.

almost at the end     right in front of me         halfway up the hill
all over the floor      just off the motorway      directly after your lesson

E. Some words can be either a preposition or an adverb.

Preposition:     I waited for my friend outside the bank.
                        We haven't seen Julia since last summer.
                        There was no lift, so we had to walk up the stairs.

Adverb:           My friend went into the bank, and I waited outside.
                        We saw Julia last summer, but we haven't seen her since.
                        There was no lift, so we had to walk up.