Use of Preposition & Common Combination And Preposition

Preposition

A preposition is a word that links a noun, pronoun, or noun phrase to some other part of the sentence.

A preposition is used to show direction, location, or time, or to introduce an object.

Here are a few common prepositions and examples :

On

 Used to express a surface of something:

• I put a book on the table.
• The pencil is on my desk.

Used to specify days and dates:

• The movie plays on Monday.
• I was born on the 23rd day of January in 1995.

Used to indicate a device or machine, such as a phone or computer:

• He has been on the computer since this night.
• She is on the phone right now.
• Their favorite movie will be on TV tonight.

Used to indicate a part of the body:

• The stick hit me on my hand.
• I wear a bracelet on my wrist.
• She kissed me on my lips.

Used to indicate the state of something:

• The house is on fire.
• Everything in this store is on sale.

At

 Used to point out specific time:

• She will meet me at 10 p.m.
• The bus will stop here at 1:45 a.m.

Used to indicate a place:

• There is a party at the his house.
• There were so many of people at the discotheque.
• He saw a football game at the stadium yesterday.

Used to indicate an email address:

• Please email me at abc@xyz.com.

Used to indicate an activity:

• He is good at drawing a portrait. 

• She laughed at my appearance.

Common Combination And Preposition
 
Prepositions and the rules concerning their usage can be confusing to learners of English as a second language. Basically, prepositions are connecting words that join objects to other parts of sentences. Preposition choice is determined by the noun, verb, adjective or particle which precedes it.

Noun + Preposition Combinations

English has many examples of prepositions coming after nouns. In such cases, the prepositions are often followed by a phrase containing a noun, as in example (a) below. They can also be followed by a noun, as in example (b), or an -ing verb, as in example (c).

(a) He always finding a great solution to his problem.
(b) They were surprised by his lack of concern.
(c) He need to call an expert at plumbing as soon as possible. 

Verb + Preposition Combinations

Many English prepositions also follow verbs. Sometimes they introduce a phrase that contains a noun, as in example (a). They can also introduce a noun, as in example (b), or an -ing verb, as in example (c).

(a) we can't depend on his generosity anymore. He has already done so much for us.
(b) Many of the town's residents relied on neighbours for help during the flood.
(c) She believes in helping people who are less fortunate than her. 

Adjective + Preposition Combinations

English also has many instances of prepositions coming after adjectives. In many cases, the prepositions precede phrases containing nouns, as in example (a), or pronouns, as in example (b). It is also possible for the prepositions to precede an -ing verb, as in (c).

(a) I was amazed at all the improvements.
(b) We were all shocked by his behaviour.
(c) Because the exam was more difficult than I expected, I'm worried about passing.