In the sentence “The old oak tree swayed in the wind,” which word is the simple subject?
Choose an answer, then check it.
Languages & ESL · Foundations
Subject and Predicate
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In 30 seconds
Every sentence makes a claim about something. The subject The person, place, or thing that a clause is about; the answer to who or what the sentence concerns. Full entry → names who or what the sentence is about, and the predicate The part of a clause that says something about the subject and is built around a verb. Full entry → says something about that subject, built around a verb. In “The ferry crosses the bay,” the subject is the ferry and the predicate is crosses the bay. Subjects and predicates can be simple or compound, and commands carry an unstated subject. Learning to spot these two parts makes your own sentences easier to check and revise.
Why this matters
When you can name the subject and predicate of a sentence, editing stops being guesswork. Unclear or broken sentences, such as fragments that leave out a piece or verbs that do not match their subjects, usually trace back to these two parts. Once you can find the subject, you can check whether the verb agrees with it, whether the sentence is complete, and whether the reader can tell who did what. The same habit transfers to questions, where the subject hides in an unusual position, and to commands, where it is not written at all. Writers who see sentences as two working parts revise faster and explain their changes with precision.
The college version
Two parts in every clause
Every clause rests on a two-part structure: a subject and a predicate. The subject names who or what the clause is about, and the predicate says something about that subject. The predicate is built around a verb: an action word such as crossed, a linking verb such as tastes, or a helping verb paired with a main verb such as has practiced. In “The ferry crosses the bay,” the subject is the ferry and the predicate is crosses the bay. In “The soup tastes salty,” the predicate is tastes salty, because the verb links the subject to a description instead of showing an action. Identifying the two parts does not require labeling every word first. It requires asking two questions: Who or what is this sentence about? And what is said about that person or thing? The answer to the first question is the subject, and everything in the clause that says something about that subject is the predicate. The same skeleton appears in every independent clause. “Birds sing” has a one-word subject and a one-word predicate. “Every spring, the young birds in the courtyard sing at first light” keeps the same two-part core beneath far more detail. Notice that the verb group can itself contain two words, as in has practiced, and the entire group belongs to the predicate.
Simple, complete, and compound
The subject of a clause may be a single word or a long phrase. The simple subject The essential noun or pronoun in a subject, the word the verb connects to. Full entry → is the essential noun or pronoun, the word the verb connects to. The complete subject The simple subject together with all the words attached to it in the clause. Full entry → includes that word plus everything attached to it. In “The old brick warehouse on Harbor Street caught fire,” the simple subject is warehouse. The complete subject is the old brick warehouse on Harbor Street. The modifiers and the prepositional phrase describe the warehouse, but they do not perform the burning. To find the simple subject, strip away descriptive words and phrases and ask what the verb connects to. Sometimes a clause has more than one subject. A compound subject Two or more nouns or pronouns joined by a conjunction and sharing one predicate. Full entry → is two or more nouns or pronouns joined by a conjunction such as and, or, or nor, and it shares a single predicate. In “Amir and Priya designed the poster,” both Amir and Priya designed, so the subject is compound. Just as a subject can be compound, a predicate can hold two or more verbs joined by a conjunction and sharing one subject. In “The gardener watered the herbs and weeded the beds,” watered and weeded both describe what the gardener did, so the predicate is compound. These patterns matter because a clause is defined by one subject-predicate pair at its core. Adding a second subject or a second verb attaches to that core; it does not automatically create a new clause.
Commands, questions, and what the distinction is for
Two common sentence types complicate the simple picture. Commands, which are imperative sentences, make a request, give a command, or offer an instruction, and their subject is not written. In “Return your books by Friday,” the sentence addresses the listener directly, and grammar references describe the unstated subject as understood you. You can prove this by turning the command into a statement: “You return your books by Friday.” Questions, which are interrogative sentences, rearrange the usual order. In “Has the team practiced today?” the subject team sits between the helping verb has and the main verb practiced. The reliable move is still the who-or-what test: restate the question as a statement, “The team has practiced today,” and the subject steps back into its familiar place. Why does this distinction earn so much attention? Sentence-level repair starts here. A fragment is an incomplete sentence, often one missing a subject or a predicate, so seeing the two parts lets you spot the gap. Agreement, the matching of a singular or plural verb to its subject, also begins with locating the true subject, because phrases between subject and verb can mislead. The rules of agreement belong to their own topic; the habit of finding the subject first is this lesson's contribution. Once the subject is found, a writer can check the verb against it and the reader can follow who did what.
Eli explains
The same idea, in plain words
Explain it like I’m 10
A sentence is built from two pieces that always work together. The first piece is the subject: the person, place, or thing the sentence is about. The second piece is the predicate: what the sentence says about that person or thing, with a verb at its center. In “The ferry crosses the bay,” the ferry is the subject and crosses the bay is the predicate. You can find the subject by asking who or what the sentence is about; everything that answers what happens next belongs to the predicate. Some sentences have more than one subject, and some have more than one verb doing the work. Commands leave the subject out on purpose, and questions move their parts around. If you can find these two pieces, you can explain most sentence problems clearly.
Picture it like this
Think of a sentence as a photograph of one event. The subject is the main figure the photograph centers on; the predicate is everything the picture shows that figure doing. Change the figure, or change the action, and you have a different photograph, just as changing the subject or the predicate makes a different sentence.
Where the picture stops working
A photograph can show several figures and actions without structure, but a sentence must organize its subjects and predicates around verbs, and those two parts can be rearranged, hidden, or joined in ways a picture never is.
Worked example
Read this sentence: “Before the storm arrived, the crew on the night shift sealed the windows and moved the supplies upstairs.” The independent clause is the crew on the night shift sealed the windows and moved the supplies upstairs. Ask who or what the clause is about: the crew. The simple subject is crew; the complete subject is the crew on the night shift. The predicate is everything said about the crew: sealed the windows and moved the supplies upstairs. It is a compound predicate because sealed and moved are two verbs joined by and, both sharing the same subject. Before the storm arrived is a dependent clause with its own subject, storm, and predicate, arrived. The structure is sound, so no repair is needed; a writer could keep the sentence as it is.
Key takeaway
Every clause names something, its subject, and says something about it, its predicate. Locate the subject first, and questions about agreement, completeness, and clarity become answerable.
Quick check
3 questions here, of 5 in this lesson’s practice set. Answers stay hidden until you check.
Which sentence has a compound subject?
Choose an answer, then check it.
A library sign reads, “Return your books by Friday.” What is the subject of this sentence?
Choose an answer, then check it.
Study tools & related lessonsYou’ll learn to · Common mistakes · Easily confused · Key vocabulary · Related
You’ll learn to
- Define subject and predicate as the two parts of every clause.
- Distinguish the simple subject from the complete subject.
- Identify compound subjects and compound predicates in original sentences.
- Explain how the subject of a command is understood even when it is not stated.
- Apply the who-or-what test to locate the subject of a question.
Common mistakes
Treating the first noun in the sentence as the subject.
Apply the who-or-what test to the verb: the subject is what the sentence is actually about, even when it appears after an introductory phrase such as after dinner or in the corner.
Confusing the object with the subject.
The object receives the action; it does not perform it. In “The chef sliced the onions,” chef is the subject and onions are the object.
Calling a sentence with two verbs two sentences.
Two verbs joined by a conjunction and sharing one subject form a single clause with a compound predicate, as in “The gardener watered and weeded.”
Hunting for a written subject in every command.
Commands address the listener directly; their subject is the understood you, so do not expect one on the page.
Easily confused
Simple subject vs. Complete subject
The simple subject is the core noun or pronoun the verb connects to; the complete subject includes it plus every word attached to it.
Compound subject vs. Compound predicate
A compound subject joins two or more subjects that share one predicate; a compound predicate joins two or more verbs that share one subject.
Declarative sentence vs. Imperative sentence
A declarative sentence states a fact with an expressed subject; an imperative sentence gives a command whose subject is understood as you.
Key vocabulary
- subject
- The person, place, or thing that a clause is about; the answer to who or what the sentence concerns.
- predicate
- The part of a clause that says something about the subject and is built around a verb.
- simple subject
- The essential noun or pronoun in a subject, the word the verb connects to.
- complete subject
- The simple subject together with all the words attached to it in the clause.
- compound subject
- Two or more nouns or pronouns joined by a conjunction and sharing one predicate.
- compound predicate
- Two or more verbs joined by a conjunction and sharing one subject.
- imperative sentence
- A sentence that gives a request, command, or instruction; its subject is understood rather than stated.
- interrogative sentence
- A sentence that asks a question, often placing an auxiliary verb before the subject.
Sources & references
- Writing for Success — 2.1: Sentence Writing — Humanities LibreTexts (book by Scott McLean, originally University of Minnesota)
- Language Foundations Handbook — Sentences: Sentence Forms — eCampusOntario Open Library
- Language Foundations Handbook — Sentences: Sentence Types — eCampusOntario Open Library
- Purdue OWL — Sentence Fragments — Purdue University Online Writing Lab
- Purdue OWL — Subject/Verb Agreement — Purdue University Online Writing Lab
EliExplains lessons are original prose written from the open, credible references above. See Copyright & Licensing.
Researched 2026-08-21
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