Verb Phrase Structure and Complements
Verb phrases are the engine of every sentence. They combine a main verb with auxiliaries, adverbs, and sometimes particles to express actions, states, and relationships. The complements that follow a verb (direct objects, indirect objects, subject complements) determine what kind of meaning the sentence carries.
Getting comfortable with verb phrase structure helps you write clearer sentences and catch errors in agreement, word order, and voice. It also helps you understand why certain verbs need certain companions to sound complete.
Verb Phrase Structure
Components of Verb Phrases
A verb phrase is built from a few key parts, each doing a different job:
- Main verb: Expresses the primary action or state. This is the core of the phrase (e.g., run, think, seem).
- Auxiliary verbs: Help the main verb express tense, aspect, or mood. You can stack more than one (has been running, might have jumped).
- Adverbs: Modify the verb or the entire phrase, adding information about manner, time, or frequency (quickly ran, often thinks, never sleeps).
- Particles: Small words that pair with a main verb to form phrasal verbs, changing the verb's meaning entirely. Look up (search for information) means something very different from look.
Types of Verb Complements
A complement is whatever a verb needs after it to complete the sentence's meaning. Different verbs need different complements.
- Direct object: Receives the action of the verb. It answers "what?" or "whom?" (She ate an apple).
- Indirect object: Tells you to whom or for whom the action is performed. It usually comes before the direct object (He gave her a gift).
- Subject complement: Follows a linking verb (like be, seem, look, become) and describes or renames the subject. It can be a noun (She is a doctor) or an adjective (The sky looks blue). These are sometimes called predicate nominatives (nouns) or predicate adjectives.
Verb-Complement Relationships
Not every verb works the same way. Some verbs demand a full set of complements; others need none at all.
- Valency refers to how many arguments (subject, objects) a verb requires. Sleep has a valency of one (just a subject), while give has a valency of three (subject + indirect object + direct object).
- Semantic roles describe the part each noun plays in the action. The agent performs the action, the patient undergoes it, and the recipient receives something. In Maria handed Tom the book, Maria is the agent, the book is the patient/theme, and Tom is the recipient.
- Subcategorization is the technical way of saying that specific verbs require specific complement types. Give needs both an indirect and a direct object to sound complete. Sleep needs neither.
Rules for Verb Phrase Structure
English verb phrases follow a set of structural rules that keep sentences grammatical:
- Word order: English uses Subject-Verb-Object (SVO) order. John ate pizza, not John pizza ate.
- Agreement: The verb must match its subject in person and number. He runs (singular) vs. They run (plural).
- Tense and aspect: Auxiliary verbs express when something happens and whether it's ongoing or completed. Has been running signals an action that started in the past and continues.
- Mood: Indicates the speaker's attitude toward the action. Indicative states facts (She runs), subjunctive expresses hypotheticals (If I were rich), and imperative gives commands (Be quiet).
- Voice: Active voice puts the agent as the subject (The cat chased the mouse). Passive voice puts the patient as the subject (The mouse was chased by the cat). Passive is formed with a form of be + the past participle.
Transitive vs. Intransitive Verbs
This distinction is about whether a verb needs an object to be complete.
- Transitive verbs require at least one object. A monotransitive verb takes one direct object (She bought a book). A ditransitive verb takes both an indirect and a direct object (He gave her a gift).
- Intransitive verbs don't take an object at all. They express a complete idea on their own (The baby sleeps).
- Ambitransitive verbs can go either way. The dog ate works fine on its own, but so does The dog ate its food. The verb eat doesn't change form; it just gains or loses an object.
- Ergative verbs are a special case: the object in the transitive version can become the subject in the intransitive version. Compare The sun melted the ice (transitive, ice is the object) with The ice melted (intransitive, ice is now the subject). The ice doesn't perform the action, yet it's the subject. Other examples include break, open, and sink.