It was the blue window that Seho broke yesterday.

[wotcha]

1. It was the blue window that Seho broke yesterday.

2. It was the blue window which Seho broke yesterday.


The above two sentence might be slightly different in meaning.



3. It was Tom that saw the accident yesterday.

4. It was Tom who saw the accident yesterday.


But we do teach 3 and 4 are interchangeable in Korea.

Then what if my students ask whether we can replace 'that' with

'which' like sentence 2. At least is 2 grammatical?

 

[abaka]

I suspect you're asking slightly the wrong question.

I think you really have in mind the distinction between restrictive and non-restrictive adjectival clauses.

The restrictive clause is the one that cannot be omitted if the object it is modifying is to be properly defined. For example, "There's the man who hit me yesterday".

The non-restrictive clause is the one that can be omitted. "There's my enemy, who hit me yesterday".

Conventionally the so-called rule has been that the restrictive clause should be introduced by the pronoun "that", and the non-restrictive clause by "which", "who", "whom".

As my two sentences show, however, the real distinction is that non-restrictive clauses involve a slight pause in speech, indicated by a comma or commas in writing.

Therefore if you mean a restrictive/non-restrictive distinction in your sentences (1) and (2), the comma is crucial.

(1) It was the blue window that [which] Seho broke yesterday. No comma, restrictive: As for the window Seho broke yesterday, it was that one out of many possible ones.

(2) It was the blue window, which Seho broke yesterday. Comma, non-restrictive: It was the blue window we've been talking about (that was the one Seho happened to break yesterday). [ "That" is no longer common in English to introduce non-restrictive clauses, but was frequent until the eighteenth or even nineteenth century. ]


In your sentences (3) and (4), the meaning is necessarily restrictive, and both sentences mean the same thing. As for the person who saw the accident yesterday, it was Tom -- out of many people.

Here, with comma, is a non-restrictictive version of the same sentence:

I saw a man standing at the corner. It was Tom, who saw the accident yesterday. "That" is no longer common here in modern English.

So, in response to your concern about what is grammatical: the non-restriction is indicated with pauses or commas, and needs a "who" or "which"; a non-restriction is indicated with the absence of a pause or a comma, and can use both "that" and "who/which".

By the way, appositive noun phrases are restrictive or non-restrictive without the relative pronoun, but are likewise signalled by the pause.

The philosopher Thales lived in Asia Minor. "Thales" restricts "philosopher". There are many philosophers.
Thales, the philosopher, lived in Asia Minor. "Philosopher" does not restrict "Thales". There is only one Thales.
Thales the philosopher lived in Asia Minor. "Philosopher" restricts "Thales". There is more than one Thales.

I bring this up to stress it's not really the words "that" or "which" that signal the meaning, but the pause or its absence.

 

[cheer965]

1. It was the blue window that Seho broke yesterday.

2. It was the blue window which Seho broke yesterday.


The above two sentence might be slightly different in meaning.



3. It was Tom that saw the accident yesterday.

4. It was Tom who saw the accident yesterday.


But we do teach 3 and 4 are interchangeable in Korea.

Then what if my students ask whether we can replace 'that' with

'which' like sentence 2. At least is 2 grammatical?

Sentence 1 : According to the structure may be written in either "cleft sentence" or "relative clause"
--> If it is " a cleft sentence" [It was the blue window that], it is written to emphasize: it was the blue window (not the other window) that Seho broke yesterday. The structure of a cleft sentence [It was + (...noun.....) that + clause]
In the structure of a cleft sentence, you can't use which is stead of that
--> If it is " a relative clause" [that Seho broke yesterday] it is written to confirm that Seho broke the window , not the other person. In the structure of a relative clause, you can use which or that
Sentence 2: It was the blue window which Seho broke yesterday.
It is written in the structure of a relative clause.
Sentences 3 and 4: Both these sentences are interchangeable though they are written in the structure of a cleft sentence or relative clause. The structure of cleft sentence:
It was + (...noun.....) that + clause
can be written : [It was + (...noun.....) who + clause] if noun is a person

 

[tzfujimino]

Hello.:-D
Whether it is the so-called "cleft sentence" or not depends on how 'it' (the subject) is used, in my humble opinion.
If I understand it correctly, 'it' in the "cleft sentence" is a "preparatory subject".
So, my point (=guess) is that if 'it' is not a "preparatory subject' (=if it's just a personal pronoun to indicate something mentioned earlier,) then 'that' or 'which' in those sentences above is used as a "genuine" relative pronoun, (which is to say that the defining relative clause functions as a postmodifier) They are not "cleft sentences".
#1 and #2 could mean the same thing. However, if #1 is the "cleft sentence", they don't mean the same thing. It really depends on the context.

 

[5jj]

Sentence 1 : According to the structure may be written in either "cleft sentence" or "relative clause"

This seems to me to be an artificial differentiation. '... that Seho broke yesterday' is a relative clause however one interprets the sentence as a whole.

In the structure of a cleft sentence, you can't use which is stead of that

You can. 'That' appears to be far more commonly used than 'which', but it's not impossible. You can certainly use 'who' for people.

 

[cheer965]

This seems to me to be an artificial differentiation. '... that Seho broke yesterday' is a relative clause however one interprets the sentence as a whole.

When we have a sentence Seho broke the blue window yesterday, we can use cleft sentence to emphasize the subject or object. 1/ It was the blue window that Seho broke yesterday.( to emphasize 'the blue window, not the other ones)
2/ It was Seho that / who broke the blue window yesterday. ( to emphasize just Seho, not the other person)

 

[5jj]

When we have a sentence Seho broke the blue window yesterday, we can use cleft sentence to emphasize the subject or object. 1/ It was the blue window that Seho broke yesterday.( to emphasize 'the blue window, not the other ones)
2/ It was Seho that / who broke the blue window yesterday. ( to emphasize just Seho, not the other person)

Fine, but in both sentences we have a relative clause.

I was suggesting that this:

According to the structure may be written in either "cleft sentence" or "relative clause"

was an artificial differentiation.

 

[wotcha]

1. It was the blue window that Seho broke yesterday.

2. It was the blue window which Seho broke yesterday.

3. It was Tom that saw the accident yesterday.

4. It was Tom who saw the accident yesterday.


Though 1 and 3 are cleft sentences to emphasize 'the blue window'

we teach students 'that' can be replaced by 'which' and 'who' like 2 and 4.


EVERY grammar book published in Korea says they are interchangeable, which I don't agree with.


Now I'm happy to know that I wasn't wrong.

I will say to my students that if you replace 'that' with a relative pronoun in a cleft sentence

the meaning will definitely change since relative clause is an adjective,

adding 'but when you take the test just follow the grammar books not to

lose your points'.


You can't even imagine how stupid English grammar books are - I mean

written by Koreans.


Thank you guys!

 

[tzfujimino]

we teach students 'that' can be replaced by 'which' and 'who' like 2 and 4.


EVERY grammar book published in Korea says they are interchangeable, which I don't agree with.


Now I'm happy to know I wasn't wrong.

I will say to my students that if you replace 'that' with a relative pronoun in a cleft sentence

the meaning will definitely change since relative clause is an adjective,

adding 'but when you take the test just follow the grammar books not to

lose your points'.


You can't even imagine how stupid English grammar books are - I mean

written by Koreans.


Thank you guys!

Hello, wotcha.
Please read 5jj's post (#5) again:

'That' appears to be far more commonly used than 'which', but it's not impossible. You can certainly use 'who' for people.

But I agree with you that it's much safer to use the "It is...that..." construction.

:-D

 

[wotcha]

Oh yes thank you for reminding me!

 

[5jj]

1. It was the blue window that Seho broke yesterday.
2. It was the blue window which Seho broke yesterday.
3. It was Tom that saw the accident yesterday.
4. It was Tom who saw the accident yesterday.

Though 1 and 3 are cleft sentences

They are all cleft sentences.

to emphasize 'the blue window' we teach students 'that' can be replaced by 'which' and 'who' like 2 and 4.

I am not sure what point you are trying to make there.

Now I'm happy to know that I wasn't wrong. I will say to my students that if you replace 'that' with a relative pronoun in a cleft sentence

But 'that' is a relative pronoun.

the meaning will definitely change since relative clause is an adjective, adding 'but when you take the test just follow the grammar books not to lose your points'.

Once again, the point you are trying to make is unclear to me.