Objects & Modifiers

Prepositional Phrases

A prepositional phrase is a preposition plus its object: under the stairs, from Lisbon. It does the job of an adjective or an adverb, so the key question is always which word it modifies. Reed-Kellogg gives it a two-line shape, and one phrase can sit inside another.

What you’ll learn

Draw a prepositional phrase: the preposition on a diagonal, its object on a horizontal
Tell an adjectival phrase from an adverbial one by the word it modifies
Hang each phrase from the word it modifies, which is not always the nearest word
Draw one prepositional phrase inside another, and say what each phrase includes
Find a prepositional phrase in a dependency tree: prep, then pobj

The phrase and its shape

A preposition is a word such as under, from, on, beside or through. It takes a noun or pronoun after it, called its object. Together they form a prepositional phrase, which modifies another word in the sentence.

Reed-Kellogg draws the phrase as two connected lines: a diagonal for the preposition and a horizontal for its object. These steps draw the figure below, The cat slept under the stairs.

Find the preposition and its object
The preposition is under, and its object is the stairs.
Find the word the phrase modifies
The phrase under the stairs tells you where the cat slept, so it modifies slept.
Draw the diagonal, then the horizontal
Drop a diagonal from slept and write under along it. At its lower end, draw a horizontal line and write the main word of the object, stairs, on it.
Hang the object's modifiers below it
The word the modifies stairs, so it hangs on a slant below the horizontal, just as it would below the base line.

“The cat slept under the stairs.”

Reed-Kellogg — one connected shape under the verb

det Determiner
nsubj Nominal subject
ROOT Root of the sentence
prep Prepositional modifier
pobj Object of preposition

Dependency — prep and pobj, with no boundary drawn

Comparing the two views

Reed-Kellogg draws under the stairs as one connected shape under slept, so you can see where the phrase begins and ends. The tree shows the same links as two arrows: prep from slept to under, then pobj from under to stairs. It draws no line around the phrase. To find the whole phrase, start at the preposition and follow every arrow down from it. The phrase is the preposition plus every word you reach, here stairs and the.

Adjectival or adverbial prepositional phrase?

The same shape does two different jobs. The job depends on the word the phrase modifies, which is the word it hangs from:

It modifies a noun → adjectival. It tells you which one or what kind: a parcel from Lisbon.
It modifies a verb → adverbial. It tells you how, when, where or why: arrived on Tuesday.
It modifies an adjective or an adverb → adverbial too: full of sand.

The most common mistake is to hang the phrase from the wrong word, often the nearest noun. The diagram makes that mistake easy to see.

Ask which word the phrase tells you about
The phrase from Lisbon tells you which parcel, so it modifies the noun parcel. The phrase on Tuesday tells you when the parcel arrived, so it modifies the verb arrived.
Check with two tests
An adverbial phrase can usually move to the front of the sentence: On Tuesday a parcel from Lisbon arrived. It still modifies the verb there, so in the Roles exercise it is a Predicate piece of its own, before the subject. An adjectival phrase stays with its noun. Replace a parcel with it, and you must remove from Lisbon too: It arrived on Tuesday works, but It from Lisbon arrived on Tuesday ✗ does not.
Hang it from the word it modifies
That word is not always the nearest one, and not always the verb.

“A parcel from Lisbon arrived on Tuesday.”

Reed-Kellogg — one phrase hangs from the noun, one from the verb

det Determiner
nsubj Nominal subject
prep Prepositional modifier
pobj Object of preposition
ROOT Root of the sentence

Dependency — both are prep; only the head distinguishes them

Comparing the two views

The diagram shows the difference at once: one phrase hangs from parcel, the other from arrived. In the tree, both prepositions have the same label, prep, so the label cannot tell you the job. Look at the word each prep arrow comes from, its head. If the head is a noun, like parcel, the phrase is adjectival. If it is a verb, like arrived, or an adjective or an adverb, the phrase is adverbial.

A third job: completing a linking verb

After a linking verb such as be or seem, a prepositional phrase can describe the subject. Then it is a predicate adjective: He is of sound mind and body. It stands on a pedestal behind the backslash. A phrase that tells where is not one: in Little Johnny is in his room it hangs from is like any adverbial phrase. The Roles exercise goes by the words. After look, appear, stay, remain, get or keep, a phrase such as at the word or at home hangs from the verb (Look at the word. We stayed at home. The word appears in the list.). After look, stay, remain, get or keep, a state such as in touch or in good health still stands on the pedestal as Pred. adjective (Let’s stay in touch.); after appear only a phrase with like, as or of does. After be, seem, become, feel, sound, smell or taste it keeps a simpler rule: one prepositional phrase and no other complement is labelled Pred. adjective and Adjectival prep. phrase, even when it tells where (Omar was in the garden.).

Phrases inside phrases

The object of a preposition is a noun, and a noun can take a prepositional phrase of its own. So one phrase can sit inside another: a second diagonal drops from the first phrase’s horizontal, and the drawing steps down and to the right.

There is no limit. In Santiago lives in a house near the top of the hill, three phrases sit one inside the other. Each inner phrase hangs from the object of the phrase before it: near from house, and of from top.

The outer phrase includes everything inside it. In We stood at the edge of the field, drawn below, the Roles exercise boxes at the edge of the field as one Adverbial prep. phrase. The object of at is the edge of the field, not just the edge. Inside it, of the field is an Adjectival prep. phrase.

“We stood at the edge of the field.”

Reed-Kellogg — a second phrase hanging off the first

nsubj Nominal subject
ROOT Root of the sentence
prep Prepositional modifier
det Determiner
pobj Object of preposition

Dependency — nesting is just another level

Comparing the two views

Here the tree is easier to read than the diagram. Each new phrase adds one level: of hangs from edge, and field from of. To see how deep the nesting goes, count the prep arrows on the path down from the verb. The Reed-Kellogg drawing has to step down and to the right, so a long chain of phrases soon becomes crowded.

Common mistakes

Hanging the phrase from the nearest noun. In Diego fixed the bike with a wrench, the phrase tells how he fixed it, so it hangs from fixed, not from bike.
Reading to + a verb as a prepositional phrase. The phrase to the airport is one, because a noun follows to. In Marta hopes to leave early, a verb follows, so to leave is an infinitive.
Reading a particle as a preposition. In Nina climbed up the ladder, up is a preposition with its own object, the ladder. In Nina picked up the box, up has no object of its own: the box is the object of picked up, and up is a particle. To test it, move the word after the object. A particle can move (Nina picked the box up), but a preposition cannot (Nina climbed the ladder up ✗).
Putting an infinitive after a preposition. Spanish says antes de salir and sin decir nada, but English uses the -ing form: before leaving, without saying anything, never before to leave ✗. The -ing word is a gerund, the object of the preposition; the tree labels it pcomp, not pobj.

Quick check

You are drawing Priya hid the key under a flat stone. Which word goes on the diagonal, which goes on the horizontal, and where do a and flat go?
Answer
The preposition under goes on the diagonal, which drops from hid: the phrase tells where Priya hid the key. The main word of the object, stone, goes on the horizontal. The words a and flat describe stone, so they hang on slants below the horizontal, just as they would below the base line.
Look at A book about whales fell off the shelf. Is each prepositional phrase adjectival or adverbial? How does the dependency tree show it?
Answer
The phrase about whales is adjectival: it tells what kind of book, so it hangs from the noun book. The phrase off the shelf is adverbial: it tells where the book fell, so it hangs from the verb fell. In the tree, both prepositions are prep, so look at their heads. The arrow to about comes from book, and the arrow to off comes from fell.
Which word does the prepositional phrase modify in Carlos cut the bread with a sharp knife? And in The soup was too hot for the children?
Answer
In the first sentence, with a sharp knife modifies cut, not the nearest noun, bread. It tells how Carlos cut the bread; the bread does not have a knife. In the second, for the children modifies the adjective hot, not soup or was. Both phrases are adverbial: one modifies a verb, the other an adjective.
In Nina works in an office near the station, one prepositional phrase sits inside the other. Which one is inside, and what does it hang from? What is the whole object of in?
Answer
The phrase near the station is inside. It hangs from office and tells which office, so it is adjectival. The outer phrase is adverbial: it tells where Nina works. The object of in is an office near the station, not just an office, because the object includes every word that hangs from its main word.

Key terms

Preposition: A word relating a noun to the rest of the sentence. Tagged IN, relation prep. Coarse category ADP. She sat on the chair. We walked through the park after lunch.
See: Determiners & Function Words
Prepositional phrase: A preposition together with its object. It does the job of an adjective or an adverb. We waited for the bus. The man in the blue coat left before lunch.
See: Grammar Basics
Object of the preposition: The noun phrase after the preposition: the sofa, not just sofa. Its main word goes on the horizontal, with its modifiers on slants below. In the tree, pobj marks only that main word. The object is that word plus every word that hangs from it, a nested phrase included. In at the edge of the field, the object of at is the edge of the field. She sat on the sofa. A letter from my aunt arrived.
See: Core Arguments
Adjectival prepositional phrase: A prepositional phrase modifying a noun. Hangs from that noun; the Roles exercise calls it an Adjectival prep. phrase. The letter from Melvin arrived. The girl with the green umbrella waited outside.
See: Articles, Adjectives & Objects
Adverbial prepositional phrase: A prepositional phrase modifying a verb, adjective or adverb. Hangs from that word; the Roles exercise calls it an Adverbial prep. phrase. He runs before breakfast. My brother is afraid of storms.
See: Adverbs · Adverb Clauses

Practice on a real sentence

Two prepositional phrases. Before you start, decide which word each one modifies: the verb sat, or a noun? In Roles, a phrase’s box holds everything nested inside it. In Dependencies, prep and pobj each occur twice, and the button count tells you how many are left.

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