gmat_perfect wrote: Mary buys cookies made with an artificial sweetener that tastes as sweet as corn syrup but that contains fewer calories than an equivalent amount of corn syrup.

---> Your first "that" is correct.
==> Your second that is not correct.

Why second that is incorrect?

Sweetener that tastes but that contains.

---> The sentence should be "Sweetener that tastes but contains".

When you have used "that" after but, you have made the sentence "SUB+VERB", which is an independent clause.

Without COMMA + BUT + Independent clause is not correct. Know the FANBOYS rule.

Thanks.

gmat_perfect, you are correct - but if not separated by a comma should not be followed by an independent clause. However, in this case "that contains..." is not an independent clause. It is a dependent clause. Hence the sentence is correct as is.

Correct: Mary buys cookies made with an artificial sweetener that tastes as sweet as corn syrup but that contains fewer calories than an equivalent amount of corn syrup.

Correct: Mary buys cookies made with an artificial sweetener that tastes as sweet as corn syrup but contains fewer calories than an equivalent amount of corn syrup.

Incorrect: Mary buys cookies made with an artificial sweetener that tastes as sweet as corn syrup but it contains fewer calories than an equivalent amount of corn syrup.

Here "it contains..." forms an independent clause and hence needs a comma to be separated from the other main clause.

I hope the above helps.

Regards,

Payal

joannabanana wrote:I'm still confused about when to use which and when to use that.

I know the first form of this sentence is correct, but is the second also correct? If not, why is it incorrect?

Mary buys cookies made with an artificial sweetener which tastes as sweet as corn syrup but which contains fewer calories than an equivalent amount of corn syrup.

Mary buys cookies made with an artificial sweetener that tastes as sweet as corn syrup but that contains fewer calories than an equivalent amount of corn syrup.

I will say that in an official question you will not have answer choices such that the only difference between the two choices is the use of which and that. Please see the discussion in the following thread:

https://www.beatthegmat.com/which-vs-that-t20509.html

joannabanana wrote:Ok, so I take it that both my original sentences were correct? So what's the rule for using which and that in these cases? Is it simply that they are interchangeable?

Technically they are not interchangeable. You use which when you present additional information about the noun. This information is not required to identify that noun. You use that when you present required information about the noun. This information is essential to identify the noun being discussed.

As gmat_perfect noted, your first sentence is not correct since which is not separated by a comma.
Also, since the author is talking about "an artificial sweetener", if we assume that there are many artificial sweeteners, then the information in the modifier is required to know which artificial sweetener is used in the cookies that Mary buys. Thus, 'that' should be used here.

If the sentence was written as follows, then comma which would be correct. This is because we know for sure that Splenda sweetener is used. The author just provides some additional characteristics of this sweetener.

Mary buys cookies made with Splenda artificial sweetener, which tastes as sweet as corn....

Hope that helps.

Regards,

Payal

Hi Mohish,

You are absolutely correct in saying that two independent clauses cannot be connected with just a comma. They need a semicolon or a comma with other conjunctions - FANBOYS or conjunctions like even though, although.

However, my post was in response to a specific comment made by one of the users. This comment was about the use of but. Also, if you pay close attention to my post, I begin by acknowledging the rule about punctuation required for connecting two independent clauses.

Why second that is incorrect?
Sweetener that tastes but that contains.
---> The sentence should be "Sweetener that tastes but contains".
When you have used "that" after but, you have made the sentence "SUB+VERB", which is an independent clause.
Without COMMA + BUT + Independent clause is not correct. Know the FANBOYS rule.

Thus, I was responding to this comment indicating that a dependent clause can follow 'but' without a comma. But when you have an independent clause after but (The "after but" part was implicit in the context of this post), you need a comma.

I hope that resolves the confusion.

Regards,

Payal