The Sentence

Lesson 2: Subjects and Predicates

Lesson: 2 of 9 Level: 🔵 Beginner

1. Lesson Overview

Every sentence in English divides into two parts. The first part tells us what — or who — the sentence is about. The second part tells us something about that person or thing. These two parts are the subject and the predicate, and together they form the backbone of every grammatical sentence in English.

Understanding the subject and the predicate is not merely a matter of terminology. It is the foundation of everything that follows in this course — agreement, tense, clause structure, reported speech, and more. Every one of those topics depends on the ability to identify what a sentence is about and what it says about that thing.

This lesson examines both parts in detail.

Objectives

By the end of this lesson, you will be able to:

• Define the subject and the predicate of a sentence
• Identify the simple subject, complete subject, and compound subject
• Identify the simple predicate, complete predicate, and compound predicate
• Recognise and correct common errors related to subjects and predicates

2. Core Content

A. The Subject

The subject of a sentence is the noun, pronoun, or noun phrase that the sentence is about. It is the element that performs the action expressed by the verb, or the element that is described or identified by the rest of the sentence.

In most English sentences, the subject comes before the verb.

Consider the following sentences:

The Nile is the longest river in the world, stretching approximately 6,650 kilometres from its source in Burundi to its delta on the Mediterranean coast. It flows northward through eleven countries.

In the first sentence, the Nile is the subject — the sentence is about the Nile and what it is. In the second, it is the subject — a pronoun replacing the Nile from the previous sentence. In both cases, the subject comes before the verb and establishes what the sentence is about.

B. Simple Subject, Complete Subject, and Compound Subject

The subject of a sentence can take three forms.

Simple subject

The simple subject is the single main noun or pronoun that the sentence is about, without any modifying words.

For example:

The surface temperature of Venus reaches 465°C. Migratory birds travel thousands of kilometres each year.

In the first sentence, the simple subject is temperature — the core noun the sentence is about. In the second, it is birds.

Complete subject

The complete subject is the simple subject together with all the words that modify or describe it.

For example:

The surface temperature of Venus reaches 465°C. The discovery of penicillin by Alexander Fleming in 1928 transformed the treatment of bacterial infections.

In the first sentence, the surface temperature of Venus is the complete subject — it includes the simple subject temperature and all the words that define and modify it. In the second, the discovery of penicillin by Alexander Fleming in 1928 is the complete subject — a long noun phrase with a great deal of modifying information attached to the simple noun discovery.

Compound subject

A compound subject consists of two or more subjects joined by a conjunction and sharing the same predicate.

For example:

Carbon dioxide and methane are the two most significant greenhouse gases produced by human activity. The Amazon, the Congo, and the Ganges are among the world’s most ecologically important river systems.

In the first sentence, carbon dioxide and methane form a compound subject — two nouns joined by and and sharing the verb are. In the second, three proper nouns — the Amazon, the Congo, and the Ganges — form a compound subject joined by commas and and.

C. The Predicate

The predicate is the part of the sentence that says something about the subject. It always contains the finite verb and may also include objects, complements, and adverbials — any additional information about the action or state expressed by the verb.

Consider the following sentences:

The tectonic plates move several centimetres every year. Marie Curie was the first person to win two Nobel Prizes.

In the first sentence, move several centimetres every year is the predicate — it tells us what the tectonic plates do and how much. In the second, was the first person to win two Nobel Prizes is the predicate — it tells us something remarkable about Marie Curie.

D. Simple Predicate, Complete Predicate, and Compound Predicate

Like the subject, the predicate can take three forms.

Simple predicate

The simple predicate is the finite verb alone — the core verb without any additional words.

For example:

The glacier retreats every summer. Scientists have discovered a new species of deep-sea jellyfish near the Mariana Trench.

In the first sentence, the simple predicate is retreats. In the second, it is have discovered — a two-word verb phrase consisting of the auxiliary verb have and the main verb discovered.

Complete predicate

The complete predicate is the simple predicate together with all the words that complete or modify it — objects, complements, and adverbials.

For example:

The Amazon rainforest produces approximately 20 per cent of the world’s oxygen. Charles Darwin published his theory of natural selection in 1859 after more than twenty years of careful observation.

In the first sentence, produces approximately 20 per cent of the world’s oxygen is the complete predicate. In the second, published his theory of natural selection in 1859 after more than twenty years of careful observation is the complete predicate — a long and detailed predicate that tells us what Darwin did, what he published, when he published it, and how long the process took.

Compound predicate

A compound predicate consists of two or more predicates sharing the same subject and joined by a conjunction.

For example:

The river rises rapidly during the rainy season and floods the surrounding plains. Darwin collected specimens, made detailed observations, and corresponded with scientists across Europe.

In the first sentence, rises rapidly during the rainy season and floods the surrounding plains form a compound predicate — two actions performed by the same subject, the river. In the second, three verb phrases — collected specimens, made detailed observations, and corresponded with scientists across Europe — form a compound predicate describing what Darwin did.

E. The Subject and Predicate Working Together

Every sentence in English — no matter how long or complex — can be analysed in terms of its subject and predicate. The table below shows how this analysis works across a range of sentence types and lengths.

For example:

The deepest point on Earth, the Challenger Deep in the Mariana Trench, reaches a depth of approximately 11,034 metres below sea level.

The complete subject here is the deepest point on Earth, the Challenger Deep in the Mariana Trench — a long noun phrase with an appositive (a renaming phrase) embedded within it. The complete predicate is reaches a depth of approximately 11,034 metres below sea level. Despite the length and complexity of the sentence, the same fundamental structure — subject plus predicate — holds.

3. Usage in Context

4. Common Errors and Corrections

5. Lesson Mastery

After completing this lesson, you should now be able to:

✅ Define the subject and the predicate of a sentence

✅ Identify the simple subject, complete subject, and compound subject

✅ Identify the simple predicate, complete predicate, and compound predicate

✅ Recognise and correct common errors related to subjects and predicates