# Teaching > General Teaching >  Grammar Query

## collinsc

Hi

I wondered if anyone can help me with a grammar query?

I have been told that the below instance, when you use which instead of that, you need to use a comma (as shown). Is that correct? If so, why..?
Does it not depend on how you continue the sentence?

The car that you left in the car park
The car, which you left in the car park


Thanks

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## Scheherazade

collinsc,

The use of "comma" is not determined by the pronoun which/that but by the type of information that follows (defining or non-defining).

You can find more detailed information on here:

http://www.edufind.com/english/grammar/rel4.cfm

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## collinsc

thank you

actually though, it says:

1. In non-defining clauses, you cannot use that instead of who, whom or which.

is this relevant?

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## mazHur

The car that you left in the car park has been stolen
The car which you left in the car park has been stolen.


I think the lines should read as above.

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## collinsc

thanks, i agree.

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## muhsin

Thanks also because I had never known this before.

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## HotKarl

The person you talked to originally was right. When you use "which," The clause it appears in must be off-set with commas. Sentences using "that" do not. But, as Scheherazade mentioned, the information you want to convey determines whether "that" or "which" is used. Let me elaborate.

When "which" is used, its use indicates a non-restrictive clause. In other words, the clause should be off-set with commas, as follows below:

"The car, which you left in the car park, has been stolen."

Now, this sentence means something entirely different than if "that," which is restrictive, is used. The above sentence means that only _one_ car is in question.

Now, lets turn our attention to the use of "that":

"The car that you left in the car park has been stolen."

This sentence indicates that the person who left the car in the car park has _many_ cars.

Make sense? It's late, and I don't know if I'm giving a good explanation.

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## SleepyWitch

I think it's the other way round,
you cannot use _that_ instead of _who_ or which in a non-defining relative clause.

defining relative clause: needed in order to identify which one you are talking about, 
no commas

non-defining relative clause: additional information that is not necessary to identify which thing or person you are talking about, commas

cf. HotKarls examples

Now when you have a defining relative clause, you can use _that_ instead of who or _which_
The boy who lives next door is nice = The boy that lives next door is nice
The books which I took out from the library is interesting = The book that I took out from the library is interesting.

London, which I've always loved, is a big city. 
here you can NOT say: London, that I've always loved, is a big city.

The boy, who goes to grammar school, has two sisters. 
you can't say: The boy, that goes to grammar school, has two sisters

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## AuntShecky

A rule of thumb: commas separate.
You would never want to separate a subject from a verb with a comma.
High school English teachers would call that a "comma splice."
You could use a comma to separate two or more independent clauses or a dependent clause that introduces a sentence: "If I were going, I would wear a hat."
In the example you cite you can either forgo the comma
completely OR use TWO commas to separate the description from the main clause of the sentence:
The car which you left in the parking lot has been stolen.
The car, which you left in the parking lot, has been stolen.
That "which" clause describes the specific clause. If you ever saw the movie, "Shattered Glass," you'll remember how the editor made the entire writing staff of the magazine go through every piece and put two commas in all the appositive clauses. 

Now, to address the difference between "which" and "that". Let me get Theo. Bernstein:
From "The Careful Writer," page 444:
_That_is better used to introduce a limiting or defining clause,_which_ to introduce a nondefining or parenthetical clause. . . .If the clause could be omitted without leaving the noun it modifies incomplete, or without materially altering the sense of what is being said --or if it could reasonably be enclosed in parentheses--
it would be better introduced by _which_;otherwise, by
_that_." Here are Theo. Bernstein's examples:

"The Hudson River, which flows west of Manhattan, is muddy." (A nondefining clause; it could be omitted or parenthesized.) But: "The river that flows west of Manhattan is the Hudson." (The clause defines "river" and
could not be omitted.)

Okay?

P.S. I love grammar questions, like Doug McGrath's character in "Company Man" a movie I saw recently on IFC.
But when I finish trying to answer them, I feel like a prig!

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## PrinceMyshkin

> You would never want to separate a subject from a verb with a comma.
> High school English teachers would call that a "comma splice."


My understanding of "comma splice" is when a comma is used to connect (splice) two independent sentences.

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## Scheherazade

> My understanding of "comma splice" is when a comma is used to connect (splice) two independent sentences.


I would agree with this. My understanding of "comma splice" is that a comma is being used instead of a full stop to join two independent clauses:

I did not want to watch football last night, I read my book.

These sentences should either be seperated by a full stop:

I did not want to watch football last night. I read my book.

Or they should be connected by a conjuction:

Since I did not want to watch football last night, I read my book.

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## PrinceMyshkin

> I would agree with this. My understanding of "comma splice" is that a comma is being used instead of a full stop to join two independent clauses:
> 
> I did not want to watch football last night, I read my book.


What a coincidence, because I didn't want to watch football, either. However, I could not read your book as it was in _your_ possession!




> These sentences should either be seperated by a full stop:
> 
> I did not want to watch football last night. I read my book.


Indeed, but what about your careless spelling?

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## mazHur

> The car which you left in the parking lot has been stolen.
> The car, which you left in the parking lot, has been stolen.


I endorse the above use of comma by AuntShecky,,,,,,,

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## Scheherazade

> Indeed, but what about your careless spelling?


I profusely apologise for the outrageous mistake; however, I would like to note that it was not a spelling mistake but a typing one.

Having said that, I am sure you will be delighted to find out that the offending finger has been subjected to the severest chastisement and has also been asked to type the letter "a" 1000 times as a well-deserved punishment.

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## PrinceMyshkin

> I endorse the above use of comma by AuntShecky,,,,,,,


In either case, it is regrettable, is it not?

The incidence of cars stolen from parking lots has been on the rise.

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## mazHur

For a better insight on the use of punctuation , I think one must refer to novels of Jane Austin.

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## blazeofglory

I never like to run after grammar and indeed there are hundreds of rules, and the only objective is I think to communicate across ideas. 
If we can put ideas across that is the end of it. 

Grammarians and purists are simply misguided lots. It is ideas usage of them matter and if there is proper communication and general acceptance that is enough and what else should we need beyond this goal.

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