Core Patterns

Imperatives & Conjunctions

Two things that break the tidy one-subject-one-verb picture: commands, which have a subject you cannot see, and conjunctions, which let one sentence hold two of everything.

What you’ll learn

Diagram a command, including its invisible subject
Tell a person being addressed from the subject of the sentence
Draw the chevron that joins two equal elements
Tell a compound subject from a compound sentence

Commands and the invisible subject

Wait. is a complete sentence. It has a verb, and it has a subject — you — but the subject is not written down. English leaves it out of every command.

The diagram puts it back, in brackets, because the structure requires a subject even when the words do not supply one. This is the only place in the notation where you write a word that is not in the sentence.

“Wait.”

Reed-Kellogg — the understood subject, in parentheses

ROOTRoot of the sentence

Dependency — a root with no subject arc at all

Comparing the two views

A genuine structural disagreement. Reed-Kellogg adds a word — the implied (you) — because its notation has a subject slot that must be filled. The dependency parse only ever describes words that are present, so it has nothing to say about the missing subject at all: Wait is simply the root, with no nsubj arc anywhere. Neither is wrong; they disagree about whether a diagram may contain something the sentence does not.

Naming the person you are addressing

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

The notation shows that literally: a vocative floats on its own short line above the diagram, connected to nothing. The clause underneath still has (you) as its subject.

Check whether the name is doing the verb
If you can answer “who sits down?” with the name, it is a subject. Here the answer is you, so Marco is not.
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, please sit down.”

Reed-Kellogg — the vocative floats free

npadvmodNoun phrase as adverbial modifier
intjInterjection
ROOTRoot of the sentence
prtParticle

Dependency — every word must attach to something

Comparing the two views

Reed-Kellogg expresses “outside the clause” as literal disconnection — the line carrying Marco touches nothing. A dependency tree cannot do that: every word must have a head, so Marco is forced to attach to sit anyway, and the relation label npadvmod is left to carry the meaning. This is one of the clearest cases where the constituency view says something the dependency view structurally cannot.

Joining equals: the chevron

and, but, or join two things of the same kind. When they join two subjects, or two verbs, or two objects, the base line forks: it splits into parallel branches that rejoin, with the conjunction on a dashed line between them.

The fork is what tells you the two branches are equals sharing everything else in the sentence. In Diego and Nina repaired the fence. there is one verb and one object; only the subject is doubled.

“Diego and Nina repaired the fence.”

Reed-Kellogg — a symmetrical fork for the compound subject

nsubjNominal subject
ccCoordinating conjunction
conjConjunct
ROOTRoot of the sentence
detDeterminer
dobjDirect object

Dependency — one subject, with the other hanging off it

Comparing the two views

The two views structure coordination completely differently. Reed-Kellogg makes the branches symmetrical — neither Diego nor Nina is subordinate to the other, which matches how coordination actually works. The dependency parse cannot express symmetry: it has to pick one, so Diego becomes the subject and Nina hangs off him as conj, with and as cc. The tree is making an arbitrary choice that the diagram avoids.

Two clauses, not two words

When the conjunction joins two things that each have their own subject and verb, it is not a compound element — it is a compound sentence, and each clause gets a base line of its own, stacked one above the other.

The test is simply whether the second half has its own subject. Diego and Nina repaired the fence has one verb, so it is a compound subject. We packed, but the taxi never came has two subjects and two verbs, so it is two clauses. Full treatment in Compound-Complex Sentences.

“We packed, but the taxi never came.”

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

nsubjNominal subject
ROOTRoot of the sentence
ccCoordinating conjunction
detDeterminer
negNegation modifier
conjConjunct

Dependency — the second clause hangs off the first as conj

Comparing the two views

Reed-Kellogg gives each clause a full base line and joins them with a dashed step-down carrying but, so “two clauses” is visible immediately. The dependency tree flattens this: it makes packed the single root and attaches came to it as conj, exactly as it attached Nina to Diego above. From the tree alone, a compound subject and a compound sentence look like the same operation.

Key terms

Imperative: A command. Its subject is an understood you, written in parentheses in the diagram and absent from the dependency tree entirely. Shut the door. Please wait here. — in both, the doer is the person addressed.
See: Sentence Types & Voice
Vocative: The person being addressed. Grammatically outside the clause, so it floats on an unconnected line above the diagram. Maria, pass the salt. We are ready, everyone.
See: Adverbs
Coordinating conjunction: and, but, or, nor, for, so, yet — the words that join equals. Tagged CC, and always cc in the tree. Tea or coffee? She tried, but the door stuck.
See: Compound-Complex Sentences
Compound element: Two or more subjects, verbs or objects sharing the rest of the clause. Drawn as a fork on one base line. Jack and Jill fell. — two subjects. She bought apples and pears. — two objects.
See: Reed-Kellogg Diagrams
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. We waited, but nobody came.
See: Compound-Complex Sentences

Practice on a real sentence

This sentence has a compound direct object — two nouns sharing one verb. Watch for the cc and conj relations in the dependency exercise, and for the fork appearing in the diagram as you label the roles.

“The agency feeds unwanted dogs and cats.”

Parts of speech

Give every word its coarse Universal Dependencies category.

Words 0/7Attempts 0Correct 0Time 0:00

Sentence — select a part of speech below, then click the word(s) it applies to

The agency feeds unwanted dogs and cats.