Prepositions

  A preposition describes a relationship between other words in a sentence. In itself, a word like "in" or "after" is rather meaningless and hard to define in mere words. For instance, when you do try to define a preposition like "in" or "between" or "on," you invariably use your hands to show how something is situated in relationship to something else. Prepositions are nearly always combined with other words in structures called prepositional phrases. Prepositional phrases can be made up of a million different words, but they tend to be built the same: a preposition followed by a determiner and an adjective or two, followed by a pronoun or noun (called the object of the preposition). This whole phrase, in turn, takes on a modifying role, acting as anadjective or an adverb, locating something in time and space, modifying a noun, or telling when or where or under what conditions something happened.

   Consider the professor's desk and all the prepositional phrases we can use while talking about it.

You can sit before the desk (or in front of the desk). The professor can sit on the desk (when he's being informal) or behind the desk, and then his feet are under the desk orbeneath the desk. He can stand beside the desk (meaning next to the desk), before the desk, between the desk and you, or even on the desk (if he's really strange). If he's clumsy, he can bump into the desk or try to walk through the desk (and stuff would fall off the desk). Passing his hands over the desk or resting his elbows upon the desk, he often looks across the desk and speaks of the desk or concerning the desk as if there were nothing else like the desk. Because he thinks of nothing except the desk, sometimes you wonder about the desk, what's in the desk, what he paid for the desk, and if he could live without the desk. You can walk toward the desk, to the desk, around the desk,by the desk, and even past the desk while he sits at the desk or leans against the desk.

           All of this happens, of course, in time: during the class, before the class, until the class, throughout the class, after the class, etc. And the professor can sit there in a bad mood[another adverbial construction].

Those words in bold black font are all prepositions. Some prepositions do other things besides locate in space or time — "My brother is like my father." "Everyone in the class except me got the answer." — but nearly all of them modify in one way or another. It is possible for a preposition phrase to act as a noun — "During a church service is not a good time to discuss picnic plans" or "In the South Pacific is where I long to be" — but this is seldom appropriate in formal or academic writing.

Prepositions of Time: at, on, and in

We use at to designate specific times.
The train is due at 12:15 p.m.

We use on to designate days and dates.
My brother is coming on Monday.
We're having a party on the Fourth of July.

We use in for nonspecific times during a day, a month, a season, or a year.
She likes to jog in the morning.
It's too cold in winter to run outside.
He started the job in 1971.
He's going to quit in August.

Prepositions of Place: at, on, and in

We use at for specific addresses.
Grammar English lives at 55 Boretz Road in Durham.

We use on to designate names of streets, avenues, etc.
Her house is on Boretz Road.

And we use in for the names of land-areas (towns, counties, states, countries, and continents).
She lives in Durham.
Durham is in Windham County.
Windham County is in Connecticut.

Prepositions of Location: in, at, and on and No Preposition
IN (the) bed* the bedroom the car (the) class* the library* school*	AT class* home the library* the office school* work	ON the bed* the ceiling the floor the horse the plane the train	NO PREPOSITION downstairs downtown inside outside upstairs uptown
* You may sometimes use different prepositions for these locations.

Prepositions of Movement: to
and No Preposition

We use to in order to express movement toward a place.
They were driving to work together.
She's going to the dentist's office this morning.

Toward and towards are also helpful prepositions to express movement. These are simply variant spellings of the same word; use whichever sounds better to you.
We're moving toward the light.
This is a big step towards the project's completion.

With the words home, downtown, uptown, inside, outside, downstairs, upstairs, we use no preposition.
Grandma went upstairs
Grandpa went home.
They both went outside.

Prepositions of Time: for and since

We use for when we measure time (seconds, minutes, hours, days, months, years).
He held his breath for seven minutes.
She's lived there for seven years.
The British and Irish have been quarreling for seven centuries.

We use since with a specific date or time.
He's worked here since 1970.
She's been sitting in the waiting room since two-thirty.

Prepositions with Nouns, Adjectives, and Verbs.

Prepositions are sometimes so firmly wedded to other words that they have practically become one word. (In fact, in other languages, such as German, they would have become one word.) This occurs in three categories: nouns, adjectives, and verbs.

NOUNS and PREPOSITIONS
approval of awareness of belief in concern for confusion about desire for	fondness for grasp of hatred of hope for interest in love of	need for participation in reason for respect for success in understanding of

ADJECTIVES and PREPOSITIONS
afraid of angry at aware of capable of careless about familiar with	fond of happy about interested in jealous of made of married to	proud of similar to sorry for sure of tired of worried about

VERBS and PREPOSITIONS
apologize for ask about ask for belong to bring up care for find out	give up grow up look for look forward to look up make up pay for	prepare for study for talk about think about trust in work for worry about

A combination of verb and preposition is called a phrasal verb. The word that is joined to the verb is then called a particle.

Sumber : http://grammar.ccc.commnet.edu/grammar/prepositions.htm