Form
The key components of a clause are its subject phrase and its predicate, which must be in agreement with one another.
Subject Phrases
The subject of any sentence is the noun phrase a) which the sentence is about, and b) which typically precedes the main verb. The subject also owns the verb, which means that the subject either performs the action or holds the state.
The nucleus of most subjects is a traditional noun or pronoun, though it may instead be other words or phrases that serve the role of nouns (like Gerunds, Content Clauses, or even Full Infinitives). In addition to the noun nucleus, a subject phrase may include a determiner or any number of modifiers, such as adjectives, prepositional phrases, Relative Clauses, appositives, etc. For example, the entire expression, “the four tired dogs lying in the shade” is a subject phrase headed by the subject noun ‘dogs’.
A subject may include multiple distinct nouns, as in “the tortoise and the hare”, in which case each noun shares a role in the verb.
For imperative clauses, the subject phrase is unvoiced, meaning it is not written or spoken, but is still understood to be a part of the sentence. For example, in the sentence “Hand me a towel, please,” the subject is understood to be ‘you‘.
Predicates
The head of a predicate is a verb string, though predicates also include complements like direct objects, predicative nominals, or predicative adjectives. Linkers and modifiers that refer back to either the verb or the complements are also a part of the predicate. Here are some examples of predicates (with the verb strings underlined):
- “slept“
- “had given her advice”
- “is the captain”
- “seems distraught”
- “would really love to join them later”
- “quietly hides inside a box”
Modifiers are optional, and the inclusion of complements depends on the valency of the verb. The only piece of the predicate that must be featured in every single sentence is the verb string.
Predicates may have multiple verbs phrases (the combination of verb strings with their modifiers and complements) connected by a linker, as in “went to the store and bought some milk.” The two verb phrases — here: ‘went to the store’ and ‘bought some milk’ — apply to the same subject.
Agreement
The subject and the verb string(s) must agree with one another. Subject-Verb Agreement means that the verb string should reflect the person and count of the subject. For example, “We knows” and “He am” do not agree (they should instead be “We know” and “He is”, respectively).
The form of the verb changes for agreement only in present tenses. The sole exception to this is that BE has different past forms for agreement.
The burden of agreement falls upon the leading auxiliary verb of each verb string. BE, HAVE, and DO each have special forms depending on whether the subject is singular or plural and on whether the subject is in the 3rd-person or otherwise. Modal verbs, on the other hand, do not change their form; they are unique in that their base form always agrees with the subject.
If there are no auxiliary verbs, the main verb then takes on the role of agreement. Present verbs take on the -s suffix (which should be -es when the last letter of the base verb is ‘ch’, ‘o’, ‘s’, ‘sh’, ‘x’, or ‘z’) when their subjects are singular and in the 3rd-person, but not otherwise.
Categories
Main vs. Subordinate
A main clause is the foundation of its sentence and is not embedded in any other clause. The structure of a main clause — whether declarative, imperative, or interrogative — determines the structure and end punctuation of the overall sentence. Every sentence needs at least one main clause.
A main clause that could be a complete sentence on its own is called an independent clause.
A subordinate clause is a clause that serves a particular role within a sentence. A subordinate clause on its own cannot be a complete sentence. Rather, subordinate clauses must be embedded inside other clauses (host clauses). Not every sentence requires a subordinate clause.
There are three types of subordinate clauses: Adverbial, Relative, and Content. See the Complex Sentences section below for more.
Host vs. Embedded
A host clause is a clause that has another clause embedded within it. In complex sentences, every main clause is also a host clause. But subordinate clauses can also be host clauses if there is yet another subordinate clause inside them.
An embedded clause is a clause that is placed inside another clause. Every subordinate clause is also an embedded clause (unless it exists by itself as a fragment, which is not a complete sentence).
It’s possible for a subordinate clause to be not only an embedded clause, but a host clause as well. Consider the second sentence in the previous paragraph as an example. In particular, consider the Adverbial Clause “unless it exists by itself as a fragment”.
- This Adverbial Clause is an embedded clause, and the main clause of the sentence — “Every subordinate clause is also an embedded clause” — is its host clause.
- But that Adverbial Clause is also a host clause because it contains an embedded Relative Clause — “which is not a complete sentence” — within it.
The structure of that example sentence looks like this: Main Clause [Adverbial Clause [Relative Clause] ]. Complex sentences like these can have multiple layers of embedded clauses.
The terms host clause and embedded clause are not about the structure or content of the clauses themselves, but rather their relationship to one another.
Applications
Simple Sentences
A simple sentence is a sentence that only has one clause: an independent clause. In most cases, we can just regard the clause and the sentence as being one and the same. But some simple sentences also include a discourse adverbial phrase — like ‘however’, ‘admittedly’, ‘on second thought’, etc. — typically at the very beginning of the sentence, before the independent clause.
Examples of simple sentences:
- “Imelda disappeared into her imagination.”
- “Frankly, Carlos forgot to feed the cat.”
- “I’m exhausted.”
Compound Sentences
A compound sentence is a sentence with multiple independent clauses that are presented side-by-side and which do not share any grammatical elements (though they probably share context).
Two clauses can be linked in the following ways:
- with a comma and a Clausal Coordinating Conjunction. The most common Clausal Coordinators are ‘but’, ‘or’, ‘then’, ‘and’, ‘nor’, and ‘yet’ (represented by the mnemonic acronym ‘BOTANY’), but others include ‘for’ and ‘so’. A comma plus a conjunction is the most popular way to form compound sentences.
- with a colon. This is generally used if the second clause is meant to be a logical conclusion that results from the setup of the first clause.
- with a semicolon. This is generally used if the second clause is meant to be a clarification of the first clause We might use it to express the same general sentiment in both clauses, but perhaps using a different perspective for each (like two sides to a coin). Alternatively, the second clause might be more specific than the first clause.
Three or more clauses are usually linked with commas or semicolons between each, then with a Clausal Coordinator before the final clauses.
Examples of compound sentences:
- “Imelda disappeared into her imagination; she does that often.”
- “Carlos forgot to water the plants, but at least he remembered to feed the cat.”
- “I’m exhausted, I’m confused, and I’m hungry.”
In most cases, every main clause in a compound sentence should have the same type of structure: declarative, imperative, or interrogative. However, we could also have an imperative clause followed by a declarative clause with a volitional or deontic verb phrase.
Complex Sentences
A complex sentence is a sentence that has one or more clauses embedded inside another clause. This sets apart two categories of clauses:
- Main clauses provide the overall framework of the sentence and host subordinate clauses.
- Subordinate clauses, which are also embedded clauses, serve a particular role within their host clause. There are three types of subordinate clauses:
- Content Clauses serve the role of nouns within the host clause.
- Adverbial Clauses serve the role of modifiers within the host clause. They behave just like prepositional phrases.
- Relative Clauses serve the role of modifiers within the host clause. Their linkers reference a particular element of the host clause while also filling a syntactic role within the embedded clause.
The linkers that bind clauses together are called Subordinating Conjunctions. Each of the three types of embedded clauses has their own set of subordinators. Information for such linkers can be found on their relevant subordinate clause pages.
Examples of complex sentences with Content Clauses:
- “We noticed that Imelda disappeared into her imagination.”
- “I told you I’m exhausted.”
Examples of complex sentences with Adverbial Clauses:
- “Carlos forgot to feed the cat even though you reminded him twice.”
- “I’m exhausted because we’ve been on the move since daybreak.”
Examples of complex sentences with Relative Clauses:
- “Imelda disappeared into her imagination, where she spends much of her time.”
- “Carlos forgot to feed the cat that his mother left him.”
While some main clauses of complex sentences can stand on their own, others are dependent upon their embedded subordinate clauses to be semantically or even grammatically complete. Such main clauses cannot then be called ‘independent’. Therefore, Insights to English recommends avoiding the term ‘independent clause’ when it comes to complex sentences.
Compound-Complex Sentences
A compound-complex sentence is a sentence that has at least three clauses: at least one main clause and at least one embedded clause; a third clause is compounded with either the main clause or the embedded clause. Beyond that, additional clauses may be compounded with or embedded in any of the other clauses.
There is no strict limit to the number of clauses that can appear in a sentence, as long as one of them is distinctly a main clause.
Advanced Concepts
Predicate Breakdown & Terminology
Here’s a look at the various elements that might be featured in a predicate. We’ll use the predicate example, “is missing and hasn’t given me new information in the past 24 hours” throughout.
- verb phrase — Most linguists consider a verb phrase to contain more than just a clause’s verbs: it’s also any complements and modifiers connected to the verb.
- eg: “is missing”
- eg: “hasn’t given me new information in the past 24 hours”
- verb string — This is less well-defined, but Insights regards a verb string as a main verb, all of its auxiliary verbs, and any negators (not, never, or no longer).
- eg: “is”
- eg: “hasn’t given”
- subject complement — This is what follows a linking verb. A predicative nominal is a noun phrase that either renames or categorizes the subject. A predicative modifier (like an adjective or a prepositional phrase) following a linking verb describes or specifies the subject.
- eg: “missing”
- verb complement — This is what follows an action verb and which completes the essential meaning of the verb phrase. A direct object is the noun that the verb acts upon. An indirect object is the recipient of the verb’s action.
- eg: “me”
- eg: “new information”
- adjunct — A modifier that adds information but is not essential to the structure of the verb phrase is called an adjunct. These may be adverbs, prepositional phrases, Adverbial Clauses, etc.
- eg: “in the past 24 hours”
Asyndetic Compounds
Although it’s rarely used in modern English, a compound sentence can be linked without the use of a conjunction, a colon, or a semicolon.
Between two independent clauses of which one is positive and the other is negative, we can have a comma and no conjunction. But a limiting and adversative adverb like ‘just’ or ‘only’ should also be featured. For example: “The politician was not just incompetent, she was corrupt.” Insights generally recommends using a semicolon instead of a comma in instances like these.
Teaching Tips
Determiners with Nouns
When a lesson focuses on parts of speech, you may want to identify the subject noun and its determiner separately. But for most other topics — especially more advanced topics like complex sentences — Insights recommends bundling the determiner together with its noun when identifying the subject. You might even want to include some crucial adjectives or other modifiers.
Presenting subject phrases instead of just subject nouns tends to provide clarity.
Fragments & Run-ons
Fragments
A fragment is an improperly-constructed sentence that either does not have a complete clause or has a subordinate clause (with its linker) without a main clause. For example:
- “Another tall tale.”
- “In my mind.”
- “When you wake up in a strange place.”
Notice that the first two examples each lack a verb, the most essential part of a predicate, which means they are not complete clauses. Meanwhile, the third example includes a linker (‘when’) that doesn’t link to anything, which means the sentence is an embedded clause without a host.
Apart from the occasional exclamatory expression, fragments are considered improper grammar, though some English speakers use them in common speech, and these days fragments are often featured in memes. The best way to help learners avoid fragments is to ensure they understand how clauses are formed.
Run-ons
Run-ons are attempts at compound and/or complex sentences for which the clauses are not properly linked together. Run-ons are often thought to be long sentences, but this is a misleading association; it’s possible for a run-on to be a short sentence, and a very long sentence isn’t a run-on if it’s properly constructed.
A couple examples of run-ons are:
- “We’re going to the movies, I can’t wait to see this film!”
- “This stinks I’m bored.”
Sometimes run-ons reflect the flow of consciousness, and they might appear in casual speech (specifically, when spoken aloud). But run-ons are virtually never acceptable in written English. The best way to help learners avoid run-ons is to ensure they understand how multiple clauses should be linked together.
Insider Access
Visit our How to Teach Clauses page on www.insightstoEnglish.com for a demonstrational video, bonus notes, printouts, a slideshow for your class, practice activities, and more.
Further Reading
| Related Concepts | Applied Grammar Topics |
|---|---|
Lexical Classes (Parts of Speech)
Noun Phrases: Determiners • Adjectives • Nouns • Pronouns
Verb Strings: Auxiliary Verbs {Modal Verbs} • Adverbs • Verbs
Subsets of Verbs: Linking Verbs • Stative Verbs • Irregular Verbs
Linkers: Conjunctions • Adpositions
