What is a Clause?

A Clause is a group of words that contains both a subjectOpens in new window and a verbOpens in new window and used as a part of a sentence.

Classification of Clauses

Clauses are of two types: independent and dependent.

Independent Clause
An independent clause expresses a complete thought—that is, it can stand alone and still make a complete sentence.

Examples include:
  • [He wanted to visit the mall] where he bought his phone.
  • [He can’t answer the phone]; [he is asleep].

Dependent Clause
A dependent clause does not express a complete thought and cannot stand alone as a complete sentence.

Examples include:
  • He wanted to visit the mall [where he bought his phone].
  • I have been thinking [whether I should accept the offer].

Classification of Dependent Clauses.

There are several dependent clauses which are classified according to their function within a sentence. Based on this, they are classified into three: noun, adjective, and adverb.

1.  Noun Clauses — A noun clause is a dependent clause that serves the function of a noun within a sentence, as “subject,” “direct object,” “predicate nominative,” “object of a preposition,” or “appositive”. Noun clauses are often introduced by signal words that mostly serve as grammatical function within the clause. A number of signal words include: “that,” “whether,” “if,” “who,” “whom,” “whose,” “which,” “what,” “when,” “where,” “why,” “how,” “whoever,” “whomever,” “whichever,” and “whatever”.

Important Hint  

Note that the signal words: “that,” “whether,” and if often do not have a grammatical function within their clause but serve only as introductory words.

Practical Examples
  • [how the chickens suddenly escaped] remains a mystery.
Clause used as subject

Here the signal word how is used as an adverb within the clause.

  • I do not know [whose car this is].
Clause used as direct object.

Here the signal word whose is used as an adjective within the clause.

  • He was asking [whether this is right].
Clause used as predicate nominative

Here, the signal word whether has no grammatical function in this clause.

  • By [what you have said], I can tell you are honest.
Clause used as object of a preposition

The signal word what is used as a direct object within the clause.

And sometimes the signal word that is only implied rather than expressed:

  • I gullibly believed (that) he is a graduate.

2.  Adjective Clauses — An adjective clause is a dependent clause that modifies a noun or pronoun. Normally, adjective clauses are introduced by words as relatives. The so–called relative words include “who,” “whom,” “which,” and “that”. However, “whose” and (sometimes “which” are relative adjectives; whereas, “when” and “where” are relative adverbs.

These so–called introductory words are called relatives because they relate the adjective clause to the words (noun or pronoun) they modify. In addition to relating the clause they introduce to the word they modify, the relative words have two other characteristics:

Practical Examples
  • The woman [who answered the phone] had a Scandinavian accent.
Clause modifies woman

The relative pronounOpens in new window who is the subject of the dependent clause. Its antecedentOpens in new window within the dependent clause of the sentence is man.

  • This is the place [where we agreed to meet].
Clause modifies place

Here, the relative adverb where modifies the infinitiveOpens in new window to meet within the dependent clause. Its antecedentOpens in new window within the independent clause of the sentence is place.

  • The booklet [that you brought] was the wrong one.
Clause modifies booklet

The relative pronounOpens in new window that is a direct object of brought within the dependent clause. Its antecedentOpens in new window within the independent clause of the sentence is booklet.

  • The boy [whose bicycle you took] is looking for you.
Clause modifies boy

The relative adjective whose modifies bicycle within the dependent clause. Its antecedentOpens in new window within the independent clause of the sentence is boy.

And sometimes the relative is implied rather than expressed:
  • The meal (that) I wanted was not in the menu.

3.  Adverb Clauses — An adverb clause is a dependent clause that modifies a verbOpens in new window, adjectiveOpens in new window, or adverbOpens in new window in another clause of the sentence. As with single adverbs and adverb phrases, adverb clauses usually answer the questions “where?” “when?” “why?” “to what extent?” or “under what condition?”

Note that adverb clauses are introduced by words known as subordinating conjunctions. They only function to connect an adverb clause to the rest of the sentence. The following chart contains the list of the most common subordinating conjunctions:

Subordinating Conjunctions
elsesowhenceso... as
except thatas...asso thatwhenever
as ifforthanwhere
thatifas much aswherever
thoughin order thatas long aswhereupon
inasmuch asas soon astillwhile
lestas thoughunlesswhether
Practical Examples
1.  It is clear [that you do not know the facts]. Clause modifies the adjective clear.
2.  She learns more quickly [than I do]. Clause modifies the adverb quickly

An adverb clause placed at the beginning of a sentence is set off with a comma, as in 3 & 4:

3.  [Because God is our refuge and strength], we will not be afraid. Modifies will not be afraid
4.  [After all is said and done], I still think you made the right decision. Modifies think

Adverb clauses elsewhere in a sentence are usually not set off with commas unless they are “nonessential” as in 5 & 6 (5 is essential, 6 is nonessential):

5.  We will start the dinner [when all the guests arrive]. Clause modifies the verb will start
6.  You must study hard, [else you will fail the test]. Clause modifies must study
Sometimes certain words in an adverb clause may be omitted and implied rather than expressed if the omitted words can be easily understood from similar words expressed in the sentence’s independent clause. This kind of adverb clause is called an elliptical clause. See an example:
  • Effiong usually solves indices problems quicker [than I]. = Effiong usually solves indices problems quicker [than I (solve)].

Identifying Dependent Clauses.

You may have observed that a number of words can be used to introduce different types of dependent clauses; that, for example, can act as a relative pronounOpens in new window (introducing an adjective clause), a signal word (introducing a noun clause), or a subordinating conjunctionOpens in new window (introducing an adverb clause). However, the lesson we should learn from this is that it is not always possible to determine which kind of clause a dependent clause is; simply from the introductory word. Thus, in deciding which kind of clause a given clause is, we must determine how the clause is used in the sentence.

Practical Examples
  • The idea [that faith and reason are mutually exclusive] was deeply debated.
Noun clause used as an appositive to the subject idea
  • The idea [that you gave me] was a good one.
Adjective clause modifying the noun idea
  • He ran so fast [that no one could catch him].
Adverb clause modifying the adverb fast