Editing Adposition (section)

==Overlaps with other categories==

===Adverbs and particles===
There are often similarities in form between adpositions and [[adverb]]s. Some adverbs are derived from the fusion of a preposition and its complement (such as ''downstairs'', from ''down (the) stairs'', and ''underground'', from ''under (the) ground''). Some words can function both as adverbs and as prepositions, such as ''inside'', ''aboard'', ''underneath'' (for instance, one can say "go inside", with adverbial use, or "go inside the house", with prepositional use). Such cases are analogous to verbs that can be used either [[transitive verb|transitively]] or intransitively, and the adverbial forms might therefore be analyzed as "intransitive prepositions". This analysis<ref>See for example ''CGEL'', pp. 612–16.</ref> could also be extended to other adverbs, such as ''here'' (this place), ''there'' (that place), ''afterward'', etc., even though these never take complements.

Many English [[phrasal verb]]s contain [[Grammatical particle|particles]] that are used adverbially, even though they mostly have the form of a preposition (such words may be called [[prepositional adverb]]s). Examples are ''on'' in ''carry on'', ''get on'', etc., and ''over'' in ''take over'', ''fall over'', and so on. The equivalents in [[Dutch grammar|Dutch]] and [[German grammar|German]] are [[separable prefix]]es, which also often have the same form as prepositions: for example, Dutch ''aanbieden'' and German ''anbieten'' (both meaning "to offer") contain the separable prefix ''aan/an'', which is also a preposition meaning "on" or "to".

===Conjunctions===

Some words can be used both as adpositions and as [[subordinating conjunction]]s:
* (preposition) '''''before'''/'''after'''/'''since''' the end of the summer''
* (conjunction) '''''before'''/'''after'''/'''since''' the summer ended''
* (preposition) ''It looks '''like''' another rainy day''
* (conjunction) ''It looks '''like''' it's going to rain again today''
It would be possible to analyze such conjunctions (or even other subordinating conjunctions) as prepositions that take an entire [[clause (grammar)|clause]] as a complement.

===Verbs===

In some languages, including a number of [[varieties of Chinese|Chinese varieties]], many of the words that serve as prepositions can also be used as [[verb]]s. For instance, in [[Standard Chinese]], 到 ''dào'' can be used in either a prepositional or a verbal sense:
* 我到北京去 ''wǒ dào Běijīng qù'' ("I go to Beijing"; ''qù'', meaning "to go", is the main verb, ''dào'' is prepositional meaning "to")
* 我到了 ''wǒ dào le'' ("I have arrived"; ''dào'' is the main verb, meaning "to arrive")
Because of this overlap, and the fact that a sequence of prepositional phrases and verb phrases often resembles a [[serial verb construction]], Chinese prepositions (and those of other languages with similar grammatical structures) are often referred to as [[coverb]]s.

As noted in previous sections, Chinese can also be said to have postpositions, although these can be analyzed as nominal ([[noun]]) elements. For more information, see the article on [[Chinese grammar]], particularly the sections on [[Chinese grammar#Coverbs|coverbs]] and [[Chinese grammar#Locative phrases|locative phrases]].

===Case affixes===

Some [[grammatical case]] markings have a similar function to adpositions; a case affix in one language may be equivalent in meaning to a preposition or postposition in another. For example, in English, the agent of a [[passive voice|passive]] construction is marked by the preposition ''by'', while in [[Russian grammar|Russian]] it is marked by the use of the [[instrumental case]]. Sometimes such equivalences exist within a single language; for example, the [[genitive]] case in [[German grammar|German]] is often interchangeable with a phrase using the preposition ''von'' (just as in English, the preposition ''of'' is often interchangeable with the [[English possessive|possessive suffix]] ''{{`s}}'').

Adpositions combine [[syntax|syntactically]] with their complement, whereas case markings combine with a noun [[morphology (linguistics)|morphologically]]. In some instances it may not be clear which applies; the following are some possible means of making such a distinction:
* Two adpositions can usually be joined with a [[coordinating conjunction]] and share a single complement (''of and for the people''), whereas this is generally not possible with case affixes;
* One adposition can usually combine with two coordinated complements (''of the city and the world''), whereas a case affix would need to be repeated with each noun ([[Latin language|Latin]] ''urbis et orbis'', not *urb- et orbis'');
* Case markings combine primarily with nouns, whereas adpositions can combine with (nominalized) phrases of different categories;
* A case marking usually appears directly on the noun, but an adposition can be separated from the noun by other words;
* Within the noun phrase, determiners and adjectives may agree with the noun in case ('''case spreading'''), but an adposition only appears once;
* A language can have hundreds of adpositions (including complex adpositions), but no language has that many distinct morphological cases.

Even so, a clear distinction cannot always be made. For example, the post-nominal elements in [[Japanese language|Japanese]] and [[Korean language|Korean]] are sometimes called case particles and sometimes postpositions. Sometimes they are analyzed as two different groups because they have different characteristics (e.g., the ability to combine with focus particles), but in such analysis, it is unclear which words should fall into which group.

[[Turkish grammar|Turkish]], [[Finnish grammar|Finnish]] and [[Hungarian grammar|Hungarian]] have both extensive case-marking and postpositions, but there is evidence to help distinguish the two:
* Turkish: (case) ''sinema'''ya''''' (cinema-''dative'', "to the cinema") vs. (postposition) ''sinema '''için''''' ("for the cinema")
* Finnish: (case) ''talo'''ssa''''' (house-''[[inessive]]'', "in the house") vs. (postposition) ''talon '''edessä''''' (house-''genitive'' in front, "in front of the house")
* Hungarian: (case) ''tető'''n''''' (roof-''[[superessive]]'', "on the roof") vs. (postposition) ''tető '''alatt''''' ("under the roof")

In these examples, the case markings form a word with their hosts (as shown by [[vowel harmony]], other word-internal effects and agreement of adjectives in Finnish), while the postpositions are independent words. As is seen in the last example, adpositions are often used in conjunction with case affixes – in languages that have a case, a given adposition usually takes a complement in a particular case, and sometimes (as has been seen [[#Grammatical properties|above]]) the choice of the case helps specify the meaning of the adposition.