A little English Grammar help

[Yahshua]

Lately I have been reading various English Grammar books. And I have one question relate to preposition and proposition. My questions are that what is the definition and the usage of preposition in English grammar? And what is the definition and the usage of proposition in the English grammar?

[Tsukuyomi]

Most prepositional words are like "at","from","near","up","down","in",and "on". Words to show a relationship between things in a sentence ^ ^

[SnoringFrog]

http://www.merriam-webster.com/dictionary/preposition

1: a function word that typically combines with a noun phrase to form a phrase which usually expresses a modification or predication

http://www.merriam-webster.com/dictionary/proposition

1 a (1): something offered for consideration or acceptance : proposal (2): a request for sexual intercourse b: the point to be discussed or maintained in argument usually stated in sentence form near the outset c: a theorem or problem to be demonstrated or performed2 a: an expression in language or signs of something that can be believed, doubted, or denied or is either true or false b: the objective meaning of a proposition3: something of an indicated kind to be dealt with <the farm was never a paying proposition>