Core Patterns

Imperatives & Conjunctions

A basic diagram has one subject and one verb, both written in the sentence. This page covers two common exceptions. In a command, the subject is not written. A conjunction such as and or but can join two subjects, two verbs or two whole clauses.

What you’ll learn

Diagram a command, with x for its unwritten subject
Tell a person being addressed (a vocative) from the subject of the sentence
Draw the chevron for two subjects, two verbs or two objects
Tell a compound subject or predicate from a compound sentence
Read cc, conj and a missing nsubj in a dependency tree

Commands and the invisible subject

A command can be a complete sentence of one word: Wait. It has a verb and a subject, but the subject, you, is not written. English leaves it out of almost every command. The verb is the base form, and its mood is the imperative.

An English statement needs a written subject; only commands can leave it out. Spanish can say Hace frío hoy with no subject, but English says It is cold today, not Is cold today.

A Reed-Kellogg base line always has something in the subject slot, even when the sentence does not say its subject. In Reed-Kellogg, x marks a word that is understood but not written.

“Wait.”

Reed-Kellogg — x for the understood subject

ROOT Root of the sentence

Dependency — a root with no subject arc at all

Comparing the two views

Here the two views disagree. Reed-Kellogg adds a mark, x, because its subject slot cannot stay empty. A dependency tree shows only the words that are there: Wait is the root, and no word hangs from it as nsubj. Neither view is wrong. In a tree, a base-form root with no nsubj is the usual sign of a command.

Vocatives: naming the person you are addressing

Marco, sit down. — Marco is not the subject. He is the person being spoken to, which is a different job, and grammatically he stands outside the clause.

The diagram shows this: a vocative floats on its own short line above the base line, connected to nothing. The clause below still has the understood you as its subject, written x.

Take the name out
If what is left, Sit down, is still a complete command to the same person, the name is a vocative. In the statement Marco sits down, the name is the subject: without it, sits down is not a sentence.
Look for the comma
A name set off by a comma at the start or end of a command is almost always a vocative.
Float it above, unconnected
No line joins it to the base line, because nothing grammatically connects them.

“Marco, sit down.”

Reed-Kellogg — the vocative floats free

npadvmod Noun phrase as adverbial modifier
ROOT Root of the sentence
prt Particle

Dependency — every word must attach to something

Comparing the two views

Reed-Kellogg shows that Marco is outside the clause: its line touches nothing. A dependency tree cannot do that, because every word needs a head, so Marco hangs from sit. The parser labels it npadvmod (a noun used like an adverb), which is wrong for a person spoken to. The right label, vocative, appears only when a person corrects the parse.

Joining equals: the chevron

The coordinating conjunctions and, but and or join two things of the same kind. When they join two subjects, two verbs or two objects, the base line forks. It splits into parallel branches, one for each joined word, with the conjunction on a dashed line between them. Where the branches meet, the lines make a point like > or <: the chevron. Where the fork sits depends on what is doubled:

Two subjects: the branches start apart and meet at a point just before the verb. In Diego and Nina repaired the fence, only the subject is doubled.
Two verbs, a compound predicate, as in Omar laughed and waved: the base line splits after the subject. Each verb keeps its own branch to the end, with its own object if it has one. The branches meet again only when both verbs share one object (see Two verbs, one object).
Two objects: the line splits after the verb, and the branches end apart. The practice sentence at the end of this page has two objects (see also Compound objects).

“Diego and Nina repaired the fence.”

Reed-Kellogg — a symmetrical fork for the compound subject

nsubj Nominal subject
cc Coordinating conjunction
conj Conjunct
ROOT Root of the sentence
det Determiner
dobj Direct object

Dependency — one subject, with the other hanging from it

Comparing the two views

Reed-Kellogg draws Diego and Nina as equals: two parallel branches, and neither word depends on the other. A dependency tree follows a fixed rule instead. The first name, Diego, is the nsubj. Nina hangs from Diego as conj, and so does the word and, as cc. In the Dependencies exercise, attach Nina and and to Diego, not to repaired.

Two clauses, not two words

Sometimes each side of the conjunction has its own subject and its own verb. Then the conjunction joins two clauses, and the sentence is a compound sentence. Each clause gets its own base line, one above the other.

The test is whether the second half has its own subject. We packed and left has two verbs but only one subject, We, so it is one clause with a compound predicate (two verbs sharing one subject). We packed, but the taxi never came has a second subject, taxi, so it is two clauses. For more, see Compound-Complex Sentences.

“We packed, but the taxi never came.”

Reed-Kellogg — two base lines, joined by a dashed step-down

nsubj Nominal subject
ROOT Root of the sentence
cc Coordinating conjunction
det Determiner
neg Negation modifier
conj Conjunct

Dependency — the second clause hangs from the first as conj

Comparing the two views

Reed-Kellogg gives each clause its own base line, joined by a dashed step-down carrying but. The tree makes packed the only root and hangs came from it as conj, the same label Nina got above. To tell them apart, look under the second joined word: came has its own nsubj (taxi); Nina has none. The verb slot reads never came: in this app never, like not, stays in the verb phrase, because the parser labels it neg (see Adverbs).

Quick check

How do you diagram Open the box carefully, and what does the dependency tree show where the subject would be?
Answer
Write x in the subject slot: the command speaks to you but does not say so. Open goes in the verb slot and box after the half vertical, as the direct object. The article the hangs on a slant under box, and carefully on a slant under Open. The tree shows nothing there: Open is the root, and no word hangs from it as nsubj.
In Carlos, hang up your coat, is Carlos the subject? How can you tell, and where does the diagram put the name?
Answer
No. Take the name out: Hang up your coat. is still a complete command to the same person, so Carlos is a vocative, the person spoken to. The subject is the understood you, written x. Carlos floats on its own short line above the base line, connected to nothing.
In The guests ate and danced, what is compound, and where does the base line fork?
Answer
The predicate is compound: ate and danced share one subject, guests. The base line forks after the subject into one branch for each verb, with and on the dashed line between them. The branches do not meet again, because the two verbs share no object.
Which of these is a compound sentence? (a) Lucas painted the door and cleaned the brushes. (b) Lucas painted the door, and Elena cleaned the brushes.
Answer
Only (b). After and comes a new subject, Elena, with its own verb, so (b) has two clauses: two base lines joined by a dashed step-down. In (a), cleaned shares the subject Lucas, so (a) is one clause with a compound predicate: one base line that forks after Lucas. The tree shows the same difference: cleaned has its own nsubj only in (b).

Key terms

Imperative: A command, made with the base form of the verb. Its subject is usually an understood you: Reed-Kellogg writes it as x in the subject slot (or as (you)), and the dependency tree leaves it out. Shut the door. Please wait here. — in both, the doer is the person addressed.
See: Sentence Types & Voice · Mood
Vocative: The person being addressed. Grammatically outside the clause, so it floats on an unconnected line above the diagram. Close the window, Omar. We are ready, everyone.
See: Adverbs · Root & Other Relations
Coordinating conjunction: and, but, or, nor, for, so, yet — the seven words that join equals. Most are tagged CC and labelled cc in the tree, but the parser reads for between two clauses as a mark and so as an advmod. Tea or coffee? She tried, but the door stuck.
See: Compound-Complex Sentences · Coordination
Compound element: Two or more subjects, verbs or objects sharing the rest of the clause. Drawn as a fork on one base line; two verbs make a compound predicate. Ana and Luis arrived early. — two subjects. Nina knocked and waited. — two verbs. We need eggs and rice. — two objects.
See: Reed-Kellogg Diagrams · Coordination
Compound sentence: Two independent clauses joined by a conjunction. Drawn as two base lines with a dashed step-down between them. She knocked, and the door opened. The bell rang, but nobody moved.
See: Compound-Complex Sentences

Practice on a real sentence

This sentence has a compound direct object: two nouns sharing one verb. In the Roles exercise, unwanted dogs and cats is one Direct object box. In the diagram, the object slot forks, and unwanted hangs before the fork because it describes both animals. In the Dependencies exercise, attach cats and and to dogs, not to feeds.

Loading the practice sentence…