Combinability of prepositions

§ 248. As a rule a preposition governs a noun. However it may also be followed by a pronoun, a gerundial phrase or a clause with nominal function, as in:

for advantage, at five o’clock, at taking measures, he was surprised at what he saw.

As prepositions indicate only the relationship between two words their position is clearly defined.

Many prepositions tend to form a phrase called a prepositional phrase, often combining either with the preceding verb or adjective, or with the following noun. Such prepositions cannot be replaced by others.

Phrases comprising verbs with prepositions to laugh at, to call for, to refer to, to look for (at, after) very often function as idioms, making one whole, so that the verb retains the preposition even if its complement is transferred, as in the passive construction:

quick action was called for, the book is often referred to.

With some polysemantic verbs the preposition often indicates its meaning, as in:

Some verbs are used with or without a preposition, with but slight difference as to content. Thus no preposition is used in the boy climbed the tree, but it is found in he climbed up the tree.

Similarly a preposition is often so closely connected with the adjective or stative it follows, that it has practically no separate meaning, and may be said to be nothing but a formal means of connecting the word with its complement:

She was afraid of the dog; The country is rich in minerals.

Prepositions with nouns or clauses may modify a preceding noun, as in:

men at work, method of teaching, the novel about which we've been speaking.