Introduction to Punctuation with 'Which' and 'That'

In English, correct punctuation is not merely a stylistic choice but a crucial element for clarity and understanding. Commas, in particular, serve as powerful punctuation marks that can delineate the structure and meaning of sentences. This article delves into the rules for using commas before the relative pronouns 'which' and 'that', enhancing your understanding and application in various contexts.

Rules for Comma Usage

Understanding when to use commas correctly can make a significant difference in the cohesiveness and readability of your writing. Here are the fundamental rules:

Do not use a comma before 'that': When 'that' introduces a defining clause (a clause that is essential to the meaning of the sentence), no comma is needed. For instance, 'The equation that is fundamental to architectural engineering made the students groan.' In this sentence, the clause 'that is fundamental to architectural engineering' is crucial for the overall meaning, so it is not separated by a comma. Use a comma before 'which': When 'which' introduces a non-defining clause (a clause that provides additional, non-essential information), a comma is required before it. For instance, 'Dry pasta, which I eat twice a week, is one of my favorite dishes.' Here, the clause 'which I eat twice a week' is supplementary information.

Examples of Comma Usage

Let's break this down with examples to better understand the application:

No Comma with 'That':

I handed in the watch that I found in the street.

The equation that is fundamental to architectural engineering made the students groan.

Comma before 'Which':

Dry pasta, which I eat twice a week, is one of my favorite dishes.

The equation, which the teaching assistant copied on the board, made the engineering students groan.

Tutorial on Comma Usage

To further refine your understanding, it's helpful to practice different scenarios:

Scenario 1: Select the sentence that requires a comma before 'which'.

A) The book that I borrowed from the library is now overdue. B) The book, which I borrowed from the library, is now overdue. C) The book that I read last year is now overdue.

Correct Answer: B) The book, which I borrowed from the library, is now overdue.

Scenario 2: Choose the correct sentence without a comma.

A) The equation that functions as a key to architectural engineering made the students groan. B) The equation, which functions as a key to architectural engineering, made the students groan. C) The equation which functions as a key to architectural engineering made the students groan.

Correct Answer: A) The equation that functions as a key to architectural engineering made the students groan.

Conclusion

Correct comma usage is a vital aspect of effective communication. Understanding the rules for using commas before 'which' and 'that' can significantly enhance the clarity and coherence of your writing. By practicing and applying these rules, you can greatly improve the readability and impact of your sentences.