Adjective Clauses

Using Adjective Clauses prevents students from making errors in sentence structure, thus avoiding Run-Ons and Comma Splices.  Like Adverb Clauses, Adjective Clauses are dependent clauses and, therefore, must be used with and independent clause.  All Adjective Clauses are introduced with a relative pronoun followed by a subject and a verb.  Used like one-word adjectives or phrases, the Adjective Clause must be positioned after the noun that it describes or modifies.  The verb tense in the adjective clause is not dependent on the tense of the verb in the main clause.
There are two types of Adjective Clauses: Restrictive and Nonrestrictive.  In a Restrictive Adjective Clause the information is necessary to identify or clarify the noun and does not use any commas.  On the other hand, A Nonrestrictive Adjective Clause is not necessary to define the noun but rather provides additional information and uses commas.
Examples:    The man who is eating in the cafeteria is my brother.  (Restrictive Adjective Clause
                         because it identifies the man.)
                         Dr. Smith, who works at Union County College, has his office on the Cranford Campus.
                        (Nonrestrictive Adjective Clause because the person has already been identified.)

Adjective Clauses used to describe objects are introduced with the relative pronoun that or which and comes as close to the noun as possible. When the relative pronoun is the subject of the Adjective Clause, the verb which follows it must agree in number with the noun that it modifies. If that is used, but it is not the subject, it may be omitted.
Examples:      The Elizabeth Campus which is one of the three campuses of Union County            
                          College is on E. Jersey St.
                          The bookstores which are located on each campus also sell t-shirts.                         
                          The highway (which) (that) I take to the college has a toll.

Adjective clauses also modify people.  These clauses are introduced with who, that, whom, or whose depending on its function in the adjective clause.  For example, if the relative pronoun is the subject of the clause who and that are used.  The verb must agree in number with the noun that it modifies.  If there is another subject and the relative pronoun is the object, then whom and that are used.  If the relative pronoun is used to show possession, whose is used.
Examples:       My aunt who (that) lives in Elizabeth works at the college. (Who is the subject of the 
                           clause.)
                           My friends who are also studying at UCC live in New York. 
                           Bill Gates whom (that) I admire has donated a lot of money to schools. (I is the subject  
                           of the clause, and whom is the object.)
                           The college whose main campus is in Cranford has three campuses.  (In this adjective
                           clause the whose shows possession to the noun, college.)

Adjective clauses can also describe or modify a noun that is related to time.  In this case the relative pronoun when is used.  Do not confuse this when with the subordinating conjunction "when" that is used in adverb clauses.  Similarly, in adjective clauses that modify a noun related to a place, the relative pronoun where is used.
Examples:           The year 1972 when the Viet Nam War ended was also the year that I moved to
                               the United States.
                               The city where I was born has recently built a mall.

Reduced Adjective Clauses
When the relative pronoun is the subject of the adjective clause, it can be reduced to a phrase.  Commas are used to separate the phrase from the rest of the sentence.
Examples:             Bill Gates, founder of Microsoft, lives in Washington state.  (Reduced from:  Bill Gates
                                who founded Microsoft lives in Washington state.
                                The novel, written by John Grisham is sold in the bookstore.  (Reduced from:  The novel
                                which was written by John Grisham is sold in the bookstore.)