354. A preposition is a word placed before a substantive to show its relation to some other word in the sentence.
The substantive which follows a preposition is called its object and is in the objective case.
A phrase consisting of a preposition and its object, with or without other words, is called a prepositional phrase.
A prepositional phrase may be either adjective or adverbial.
Thus, in the first example, of nuts is an adjective phrase modifying the noun heap, and on the floor is an adverbial phrase modifying the verb lay. In the second sentence, the verb stood is modified by two adverbial phrases, behind the tree and for some time.
355. The following list includes most of the prepositions:
Note. Such expressions as by means of, in accordance with, in spite of, etc., are really phrases, but may be regarded as compound prepositions.
Several participles like concerning, considering, pending, are common in a prepositional use and are therefore included in the list (§ 339).
For a (a form of on) in abed, asleep, afire, a-fishing, etc., see § 352.
Per is confined to the strictly commercial style except in such expressions as perforce, per cent, per annum (§ 179).
356. A preposition may stand at the end of a sentence or clause.
Note. This order, though informal, is common in the best authors; but, if carelessly used, it may result in awkwardness of style. Sometimes a relative which is the object of the preposition is omitted (see § 151). Thus, in the second sentence, which might be dropped, and the object of in would then be “which, understood.” For “He was laughed at,” and the like, see § 251.
In poetry a preposition sometimes follows its object directly: as,—“Barefoot plod I the cold ground upon” (Shakspere).
357. Certain adverbial expressions like “on Sunday,” “on March first,” occur both with and without the preposition.
Note. The forms without on are good colloquial English, but are avoided in the more formal style. No preposition need be supplied in parsing. The noun is an adverbial objective (§ 109).
358. Care is required in the use of pronouns as the objects of prepositions.
359. Several words are used either as adverbs or prepositions.
| As Adverb | As Preposition |
|---|---|
| I fell down. | I fell down the steps. |
| Stand by! | He stood by the window. |
| A big dog ran behind. | A dog ran behind the carriage. |
| Keep off! | Keep off the grass. |
For words used either as prepositions or as conjunctions, see pp. 152–154.
360. Prepositions show various distinctions in use and meaning which must be learned by practice and by the study of synonyms in a large dictionary.