CLAUSES

A clause is a systematic construction containing a subject and a verb forming either part of a sentence or constituting a whole simple sentence

DEPENDENT/INDEPENDENT CLAUSES

Any clause beginning with a subordinating word like what, that, who, which, when, since, before, after, or if is a dependent clause (sometimes called a subordinate clause). Dependent clauses, like phrases, function as grammatical units in a sentence -- that is, as nouns, adjectives, and adverbs.

Both of the following sentences are independent clauses (sometimes called main clauses). They also can stand alone as whole, simple sentences.

I went to school.

Much time had elapsed.

In the following sentences, the first clause is dependent; the second clause is independent.

When I went to school, I studied my lessons.

Since much time had elapsed, she remained at home.

Note: In the last two sentences "I studied my lessons" and "she remained at home" are complete statements. But the clauses "when I went to school" and "since much time had elapsed" do not express complete thoughts. They depend upon the independent statements to complete their meanings. Both of these dependent clauses function as adverbs.

NOUN CLAUSES

A noun clause is a dependent clause used like a noun, that is, as a subject, direct object, indirect object, or object of preposition. Noun clauses are usually introduced by that, what, why, whether, who, which, how, whoever, or whatever. Some of these introductory words can introduce both noun and adjective clauses, since the manner in which the clause is used in the sentence, and not its introductory word, determines its classification. Most sentences containing noun clauses differ from those containing adjective and adverbial clauses in that with the clause removed they are no longer complete sentences.

Your plan is interesting. The subject is the noun plan.

What you intend to do is interesting. The noun clause is the subject of the verb "is." Notice that the noun "plan" can be substituted for the noun clause.

Tell me what you intend to do. The noun clause is the direct object of the verb "tell." Again the clause is a substitute for the noun "plan."

I am interested in what you intend to do.

The noun clause is the object of the preposition IN.

I will give whoever loses the game a box of candy. The noun clause is an indirect object.

This use of the noun clause is rare.

ADJECTIVE CLAUSES

An adjective clause is a dependent clause that modifies a noun or pronoun. The common connective words used to introduce adjective clauses are the relative pronouns who (and itsinflected forms whom and whose), which, that, and relative adverbs like where and when.

(where and when can introduce all three kinds of clauses.)

The bold clauses in the following sentences are all adjective clauses:

He is a man who is respected by everyone.

Mr. Jones, whose son attends the University, is our friend.

He saw the place where he was born.

It was a time when money did not count.

Adjective clauses are classified as essential (restrictive) and nonessential (nonrestrictive.)

An essential clause, as its name implies, is necessary in a sentence because it identifies or points out a certain person or thing; a nonessential clause adds information about the word it modifies, but it is not essential in pointing out or identifying a certain person or thing.

Thomas Jefferson, who was born on the frontier, became President.

The name Thomas Jefferson has identified the person, and the bold clause is not essential.

A person who loves to read will never be lonely.

The bold adjective clause is essential in identifying a particular kind of person.

My father, who was a country boy, has made a success of his life.

Since a person has only one father, an identifying clause is not essential.

The girl by whom he sat in class is an honor student.

The bold adjective clause is essential to the identification of girl.

To determine whether an adjective clause is essential, you may apply this test: read the sentence leaving out the adjective clause and see whether the omission changes the meaning of the sentence. Try this test on the following sentence:

Airplanes, which are now manufactured in great numbers, were very necessary during the war.

Omission of the adjective clause does not change the basic meaning of this sentence. The underlined adjective clause is therefore nonessential and should be set off by commas.

Now read the following sentence, leaving out the underlined adjective clause:

Airplanes that are not carefully inspected should never be flown.

This adjective clause is necessary (therefore essential) for the meaning of the sentence.

ADVERBIAL CLAUSES

An adverbial clause is a dependent clause which modifies a verb, an adjective, or an adverb. It is used to show time, place, cause, purpose, result, condition, manner, or comparison and is introduced by a subordinating conjunction. Common subordinating conjunctions and their uses are listed below:

1. Time (when, before, since, as, until, while, after, whenever)

     After I backed up my files, the disk controller failed.

2. Place (where, wherever, whence, whither)

    His popularity dropped wherever people knew him.

3. Cause (because, since, as)

    Because he was late for a meeting, he ran up the stairs.

4. Purpose (in order that, so that, that)

    So that fairness was exercised, all the students missed recess for talking.

5. Result (so...that, such...that)

     So everyone could enjoy the film, that noisy speaker had to be repaired.

6. Condition (if, unless)

     If it continues to rain, commencement exercises will be moved indoors.

8. Manner (as, as if, as though)

     She strode toward the podium as if she had won the contest.

9. Comparison (as, than)

    The trip is more expensive than I can afford.

    Note: Introductory adverbial clauses are set off by commas.