Rule: Who refers to people. That and which refer to groups or things.

Example: Anya is the one who rescued the bird.

Example: Lope is on the team that won first place.

Example: She belongs to an organization that specializes in saving endangered species.

Rule: That introduces essential clauses while which introduces nonessential clauses.

Example: I do not trust editorials that claim racial differences in intelligence.

We would not know which editorials were being discussed without the that clause.

Example: The editorial claiming racial differences in intelligence, which appeared in the Sunday newspaper, upset me.

The editorial is already identified. Therefore, which begins a nonessential clause.

NOTE: Essential clauses do not have commas surrounding them while nonessential clauses are surrounded by commas.

Rule: Do not use that twice in a row in a sentence.

Example: That is a problem which can’t be solved without a calculator.

The above sentence would be better written as follows:
That problem can’t be solved without a calculator.

Example: That is a promise which cannot be broken.

Again, the above sentence could be rewritten:
That promise cannot be broken.

Rule: Whenever you have more than one that or which in a sentence, see if you can rewrite it in a way that both shortens your sentence and removes at least one that or which.

Rule: Put that in the sentence when it is implied.

Example: Did you know he went to the University of Florida? OR
Did you know that he went to the University of Florida? (Correct)

This entry was posted on Saturday, May 10, 2008 at 1:21 am and is filed under Who / Whom / Whoever / Whomever. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.