An antecedent is the noun to which a pronoun refers. So you have to watch out that you don't divorce the happy couple--pronoun and antecedent. And the word "antecedent" suggests that the original noun must proceed the pronoun which refers to it.

TYPES OF PRONOUNS
 

Type	Examples	Explanation
Personal	I, me, you, us, his, hers	refer to people and things
Relative	who, whose, which, that	begin dependent clauses
Demonstrative	this, these, that, those	point to specific nouns they replace
Interrogative	who, which, what, whose	used in questions
Intensive	herself, themselves, himself	repeat and emphasize a noun or pronoun
Reflexive	herself, themselves, himself	rename a proceeding noun or pronoun
Indefinite	one, anyone, somebody, nobody	refer to general, nonspecific persons or things
Reciprocal	one another, each other	refer to separate parts of a plural noun

GUIDELINES FOR USING PRONOUNS PROPERLY
 

1. Pronouns must refer clearly to their antecedents

NO: When Mark and Tom come home, he will call Fred.
YES: When Mark and Tom come home, Mark will call Fred.
2. Keep pronouns close to their antecedents; don't separate them with a lot of intervening text. Pronoun references should be consistent from one sentence to the next, or at most within one paragraph.

NO: The statement that Dr. Parker made and that she issued as a formal warning infuriated the mayor, who knew it would alarm the public.
YES: Issued as a formal warning, Dr. Parker's statement alarmed the public, and it infuriated the mayor.
3. The pronoun should point clearly and directly to its antecedent:
• Make sure your pronoun refers to a noun, not its modifier (like an adjective)

NO: From animated films such as Fantasia in 1940 to Mulan in 1998, Disney studios have raised it to an art form.
YES: From films such as Fantasia in 1940 to Mulan in 1998, Disney studies have raised animation to an art form.
• Make sure your pronoun does not refer to a possessive form of a noun

NO: Sally's case is in trouble. Does she know that?
YES: Sally is in trouble with this case. Does she know that?
• Use this, that, which, and it either directly with the noun to which they refer, or very closely with that noun.

NO: The paper proposed to link cancer and secondary smoke.This was established.
YES: The paper proposed to link cancer and secondary smoke.This connection was established.
4. Avoid indefinite antecedents for it, they, and you.

NO: It will rain tomorrow.
YES: We are expecting rain tomorrow.
5. Avoid using it as both an expletive and a pronoun in the same sentence or paragraph.

NO: It is clear that it is shirking its responsibilities
YES: It is clear that the committee is shirking its responsibilities.
BETTER: Clearly the committee is shriking its responsibilities.
6. Use relative pronouns correctly
• Who refers to specific people, divinities, or personified animals
• That refers to animals, things, or non-specific people
• Which refers to animals and things, never people
• who, that, which can be used in either essential or nonessential clauses: an essential clause means that it is essential to understanding which specific noun is referred to; nonessential means that the information in the phrase is not essential to understanding the noun. E.g.: an essential clause: People who are constantly angry become stressed. A nonessential clause: Jim, who is constantly angry, has become stressed.
• Don't overuse which or that

1. Provide a clear noun placed close to the pronoun
2. Get rid of the pronoun; put the correct noun or a close substitute in its place
3. Completely change the sentence to get rid of the unclear pronoun

WORKSHEET

In the sentences below revise so pronouns refer clearly to their antecedents:

1. Though storm experts generally understand the preconditions of severe storms, they are unsure of details--which is a problem for the millions who live in Tornado Alley.
2. These have killed about 18,000 people over the last 200 years.
3. It can contain winds of 200 miles per hour, or even higher.
4. The updraft of a tornado generally narrows, causing it to spin even faster. This can cause severe damage during the peak of a storm.
5. This tendency to spin (called voriticity) is a quality of the air itself which can interact with the updraft of a thunderstorm, which can spawn a tornado.

1. Unfortunately, archaeologists have only recently undertaken it in the context of the European Contact Period.
2. In the past they somewhat rigidly saw it as the ending point of prehistory, when Native Americans came into the orbit of Western Civilization.
3. This was apparent especially because archaeologists tended to be preoccupied with the classification of discrete periods in the past, rather than with the processes of cultural change.
4. These were given names such as Paleo-Indian, Archaic, Woodland, and so on.
5. In short, these narrowly constrained the interests of archaeologists.