A reader has asked for help in distinguishing noun, adjective, and adverb clauses.
First, what is a clause?
A clause is a group of words that contains a subject and a finite verb. (A finite verb shows time such as present, past, or future.)
Clauses are of two main kinds: independent and dependent.
An independent clause (also called a main clause) can stand alone as a complete thought.
The boat is leaking.
Cats sleep most of the time.
Elizabeth I ruled England for nearly forty-five years.
We will plant a large garden this year.
A dependent clause (also called a subordinate clause) contains a subject and finite verb, but does not express a complete thought.
because the guard was sleeping
who lived in a shoe
what I believed at the time
Dependent clauses function as adverbs, adjectives, and nouns.
Like an adverb, an adverb clause can tell when, where, why, or how an action takes place.
The prisoner escaped because the guard was sleeping. (adverb clause, tells why the prisoner escaped)
He found the book where he had left it. (adverb clause, tells where he found the book)
Like an adjective, an adjective clause tells more about a noun. Adjective clauses are easy to identify because they follow the noun they qualify. They usually begin with who, whom, whose, that, or which.
The old woman who lived in a shoe had several children. (adjective clause, tells more about the noun woman)
Is that the face that launched a thousand ships? (adjective clause, tells more about the noun face)
There goes the dog whose owner never picks up after it. (adjective clause, tells more about the noun dog)
The man whom I met last night is joining us for breakfast. (adjective clause, tells more about the noun man.)
Adjective clauses may also begin with the conjunctions when, where, or why.
Note: Some folks cling to the superstition that “time when,” “place where,” and “reason why” are embarrassments to be avoided, but that’s another post. The constructions are perfectly acceptable English.
I visited the field where Magna Carta was signed. (adjective clause, tells more about the noun field)
I remember a time when real people answered the telephone. (adjective clause, tells more about the noun time)
He never disclosed the reasons why he resigned. (adjective clause, tells more about the noun reasons)
Like a noun, a noun clause can function as the subject, object, or complement of a verb or as the object of a preposition.
Unlike adverb clauses and adjective clauses, a noun clause can be more difficult to identify because of the way it relates to the main/independent clause.
The other two kinds of clause are easy to see because they are external to the main clause and relate to a word in the main clause. The noun clause is an integral part of the main clause, functioning as subject, complement, or object.
Words that often introduce a noun clause are who, what, why, where, and when. Words that can also introduce a noun clause are which, that, whoever, whatever, wherever, and whenever.
The fact that several of these words can also be used to introduce adjective and adverb clauses adds to the difficulty of identifying a noun clause.
What I believed at the time proved false. (noun clause, subject of the verb proved)
Most people ignore whatever he says. (noun clause, object of the verb ignore)
Ignorance of the facts was why he kept changing his mind. (noun clause, complement of the verb was)
The office manager left a note on the refrigerator for whoever was stealing yogurt. (noun clause, object of the preposition for)
Note: The last example illustrates a construction that often trips up speakers who instinctively want to use the form whom after the preposition. When the object of the preposition is an entire clause, the choice must be who because the word is the subject of the verb in the clause.