Crystal W wrote:15. Carnivorous mammals can endure what would otherwise be lethal levels of body heat because they have a heat-exchange network which kept the brain from getting too hot.
　　(A) which kept
　　(B) that keeps
　　(C) which has kept
　　(D) that has been keeping
　　(E) having kept
I understand I should use present tense, but my question is about which and that, restrictive clasue and nonrestrictive clause. First, here we use that, is that meaning that keeps the brain from getting too hot an appositive clause of heat-exchange network? Second, can I use which keeps? in this, which refers to heat-exchange network(a noun.) Or I have to add a comma before which? Third, what's the difference between restrictive clause and nonrestrictive clause? if there must be a comma before nonrestrictive clause? Is this a signal of nonrestrictive clause? Also, in OG, it said "In (A) and (C), which introduces a restrictive clause. Some writers follow the convention that which can only be used for nonrestrictive clause, but insistence on this rule is controversial, and both (A) and (C)can be rejected on other grounds." Can you explain more about this point?
Thanks in advance![/b]

"Which" is typically considered nonrestrictive, meaning that when "which" serves as the subject of a modifying clause, the clause is not essential to the meaning of the thing modified. For example: Dave's car, which is parked in the driveway, is a red sedan. The nonrestrictive modifier "which is parked in the driveway" is giving you extraneous information about the car. I learned in school that you can thinking of this clause as being introduced with a parenthetical (by the way.) If the sentence were written without the modifier, it's just Dave's car is a red sedan the core meaning is still intact. The implication here is that I have only one car, and it's a red sedan.

"That" is typically considered restrictive, meaning that when it serves as the subject of a modifying clause, the clause is essential for the thing it's modifying. For example: The car that is parked in the driveway is a red sedan. Now "that is parked in the driveway" is important information and I'm using it to explain which car I'm talking about. The implication is that there are multiple cars, but I'm only writing about the one in the driveway, as opposed to the one on the street, etc. If I were to remove the modifier, I'd lose crucial information.

Notice that in the first case, the nonrestrictive modifier was set off by commas, and in the second case, the restrictive modifier was not set off by commas.

When the OG claims Some writers follow the convention that which can only be used for nonrestrictive clause, but insistence on this rule is controversial they're simply pointing out what you probably already gathered - that most english speakers pay little attention to this distinction. (My students who grew up learning British English are always baffled that this is something that American students (sometimes) learn in school.) Because nonrestrictive clauses typically follow a comma, when "which" serves as the subject of a nonrestrictive clause, it should follow comma. In A and C, "which" is the subject of the modifying clause, but does not follow a comma, making it seem as though the clause, is, in fact, restrictive, rather than nonrestrictive. The explanation is simply pointing out that even if you had no idea about this distinction, you could still use verb tense to eliminate A and C.

DavidG@VeritasPrep wrote:

Crystal W wrote:15. Carnivorous mammals can endure what would otherwise be lethal levels of body heat because they have a heat-exchange network which kept the brain from getting too hot.
　　(A) which kept
　　(B) that keeps
　　(C) which has kept
　　(D) that has been keeping
　　(E) having kept
I understand I should use present tense, but my question is about which and that, restrictive clasue and nonrestrictive clause. First, here we use that, is that meaning that keeps the brain from getting too hot an appositive clause of heat-exchange network? Second, can I use which keeps? in this, which refers to heat-exchange network(a noun.) Or I have to add a comma before which? Third, what's the difference between restrictive clause and nonrestrictive clause? if there must be a comma before nonrestrictive clause? Is this a signal of nonrestrictive clause? Also, in OG, it said "In (A) and (C), which introduces a restrictive clause. Some writers follow the convention that which can only be used for nonrestrictive clause, but insistence on this rule is controversial, and both (A) and (C)can be rejected on other grounds." Can you explain more about this point?
Thanks in advance![/b]

"Which" is typically considered nonrestrictive, meaning that when "which" serves as the subject of a modifying clause, the clause is not essential to the meaning of the thing modified. For example: Dave's car, which is parked in the driveway, is a red sedan. The nonrestrictive modifier "which is parked in the driveway" is giving you extraneous information about the car. I learned in school that you can thinking of this clause as being introduced with a parenthetical (by the way.) If the sentence were written without the modifier, it's just Dave's car is a red sedan the core meaning is still intact. The implication here is that I have only one car, and it's a red sedan.

"That" is typically considered restrictive, meaning that when it serves as the subject of a modifying clause, the clause is essential for the thing it's modifying. For example: The car that is parked in the driveway is a red sedan. Now "that is parked in the driveway" is important information and I'm using it to explain which car I'm talking about. The implication is that there are multiple cars, but I'm only writing about the one in the driveway, as opposed to the one on the street, etc. If I were to remove the modifier, I'd lose crucial information.

Notice that in the first case, the nonrestrictive modifier was set off by commas, and in the second case, the restrictive modifier was not set off by commas.

When the OG claims Some writers follow the convention that which can only be used for nonrestrictive clause, but insistence on this rule is controversial they're simply pointing out what you probably already gathered - that most english speakers pay little attention to this distinction. (My students who grew up learning British English are always baffled that this is something that American students (sometimes) learn in school.) Because nonrestrictive clauses typically follow a comma, when "which" serves as the subject of a nonrestrictive clause, it should follow comma. In A and C, "which" is the subject of the modifying clause, but does not follow a comma, making it seem as though the clause, is, in fact, restrictive, rather than nonrestrictive. The explanation is simply pointing out that even if you had no idea about this distinction, you could still use verb tense to eliminate A and C.

Thank you for your explanation and it is really clear. I have a small question just to make sure. You said that keeps...is the restrictive modifier, is that a restrictive attribute clause? I am not sure if modifier and attribute are the same meaning?

Thank you for your explanation and it is really clear. I have a small question just to make sure. You said that keeps...is the restrictive modifier, is that a restrictive attribute clause? I am not sure if modifier and attribute are the same meaning?

I'll be honest - I'd never seen "attributive" as a technical grammatical term before. So I looked it up. And it's not exactly interchangeable with the term 'modifier,' but rather it's a type of modifier. An attributive modifier is one that modifies the head noun in a given phrase. (the head noun is just the main noun of the phrase.) So the only real difference, so far as I can tell, is that "modifiers" would encompass other parts of speech, such as adverbs, which can modify verbs or adjectives, while "attributives" have to modify head nouns. But just to be clear, internalizing this distinction will be of no help on the GMAT, and should be trotted out mainly to annoy people at dinner parties