This short video explains the important concept of the usage of "which" versus "that" from the perspective of GMAT sentence correction questions.
Short answer: "which" is generally preceded by a comma and used for providing extra information; "that" is generally not preceded by a comma and is used for providing information critical for the intended meaning of a sentence.
"Which" Versus "That" on GMAT
One very important grammatical concept to keep in mind while preparing for GMAT is the difference between "which" and "that". The difference in how the two words are used and their exact meanings are quite subtle and often not adhered to in everyday speech and writing; as a result, many GMAT students have difficulty in mastering this concept. This short article will cover the usage of "which" vs "that" from the perspective of GMAT sentence correction; understanding this concept will help you catch this subtle mistake in the GMAT sentence correction and eliminate incorrect answer choices.
"Which" is generally preceded by a comma and is used to provide extra information about a noun. On the GMAT, all extra information present in a sentence must be presented between two commas and its removal must not affect or alter the core meaning of the sentence; this means that if the phrase containing "which" is removed, the sentence should still be complete, grammatically correct, and convey its core meaning. Let us illustrate this concept, through the following example:
Example 1: France would play against Brazil, which is a stronger team, in the finals.
A careful reading of this sentence will show you that the phrase "which is the stronger team" is extra information that does not affect the core meaning of this sentence, France will play against Brazil in the finals. Thus, even if the phrase "which is the stronger team" is removed the core meaning of the sentence does not change; this means that Example 1 is a correct sentence.
To recap, the two salient points to take away from this explanation are that, on the GMAT, "which" will typically follow a comma and the phrase containing the word "which" will convey extra information and it should be able to be removed, without affecting the sentence's core meaning. These are the points that we will find contrast against, as we examine the use of "that" on GMAT.
"That" is not preceded by a comma and is used to give information that is critical for the correct meaning of the sentence to be conveyed. Let us take a look at another example, to understand this concept with more clarity.
Example 2: The team, which scores more goals, will be the winner.
If we remove the phrase "which scored the most goals", the sentence becomes "The team will be the winner.' Thus, the core meaning of the sentence will be lost and we "that" should be used here, rather than "which". The correct sentence is:
The team that scores more goals will be the winner.
This article has deliberately been kept brief; for a more elaborate explanation, please refer to Experts' Global's Stage One Sentence Correction videos.