1. She is the perfect accountant which/*who/*that her predecessor was not.

  2. This is not the type of modern house which/* that/* ( ) my own is.

(CGEL, Quirk et al, 1985, Sec 17.14) Quote

Could someone please explain to me why the authors marked the other two relative words as wrong, especially "that". They didn't explain, nor have I learned a grammar rule which supports this. Besides, I have found many examples with the same pattern using "that".

the perfect xxx that...

  • 1
    I hope @BillJ sees this
    – gotube
    Jul 25, 2022 at 6:35
  • You neglected to quote this relevant explanation from Q&G: S, O, C, A in the survey below means that the relative pronoun functions respectively as subject, object, complement, and adverbial . . . Jul 25, 2022 at 7:30
  • @gotube Billj says he doesn't have faith in Quirk et al, and he always follows CGEL by Huddleston and Pullum. :)
    – ForOU
    Jul 25, 2022 at 7:58
  • @Robbyzhu BillJ is a convert, a proselyte, of CGEL. At times even too much.
    – Mari-Lou A
    Jul 25, 2022 at 8:42
  • Araucaria gave a much better answer than mine on EL&U.
    – gotube
    Jul 25, 2022 at 18:59

2 Answers 2


In the first sentence, "that" is incorrect because it's in a non-defining relative clause (also called non-identifying or non-restrictive relative clause). There's no comma—which I think is a mistake in the book—but this clause cannot be understood as a defining relative clause (also called identifying or restrictive relative clause). Non-defining relative clauses can only have "which" or "who(m)" as the relative pronoun, so "that" is incorrect.

In the same sentence, "who" is also incorrect. It seems obvious that the antecedent is "the perfect accountant", which is a person, so the pronoun should be "who", but that's not the case.

You might also think that it's something about "the perfect accountant" being a concept, and not a real person, but the same grammar applies if we use the same structure with a noun phrase that clearly represents a real person:

A. She has me, which her predecessor did not.

We get a clue from these sentences:

B. She has a daughter, which I do not.
C. She is employed, which I am not.

In B. "which" seems to refer to the verb phrase, "have a daughter", and not just "a daughter". In C., there is no noun at all, so "which" cannot refer to any noun, yet the sentence is still grammatical.

So, the answer is that relative clauses can refer to things other than nouns, including verb phrases. In the case of your example sentence, "which" refers to the verb phrase, "is the perfect accountant", rather than just "the perfect accountant". We know what it refers to from context. In this case, it doesn't make any sense for "she", "the perfect accountant" and "her predecessor" to all be the same person, so the relative clause must be talking about "is the perfect accountant". This phrase is not a person, so it requires the pronoun "which".

As for sentence 2, I can't find anything wrong with any of the choices given. I don't know how reputable that books is, but given that I found a mistake in the first sentence, maybe it's not that good.

  • I'd venture to say that CGEL is a solid reliable reference book which has been cited frequently on EL&U en.wikipedia.org/wiki/…. Can you please explain why there should be a comma "She is the perfect accountant (,) which her predecessor was not."? Why can't it be a defining clause? this clause cannot be understood as a defining relative clause I think it is a defining clause precisely because the comma is unnecessary, e.g. Here are some books which I have read. and "We've found the accountant who/that/which fits the job position.”
    – Mari-Lou A
    Jul 25, 2022 at 8:36
  • @Mari-LouA In a defining relative clause, (1) the relative clause defines which X the referent is. Also, in a defining relative clause, (2) the referent and the entire relative clause form a single noun phrase together. Neither is true in this case. (1) "The perfect accountant" is already unique, and does not require further definition to distinguish it from among others, as the books and accountant do in your examples. The clause "which her predecessor was not" does not define which perfect accountant is referred to; and ....
    – gotube
    Jul 25, 2022 at 15:00
  • @Mari-LouA ...(2) "the perfect accountant which her predecessor was not" would have to be a single, meaningful noun phrase, which it isn't. It's two separate ideas, "the perfect accountant" and "her predecessor was not the perfect accountant"
    – gotube
    Jul 25, 2022 at 15:00
  • I think it's possible to interpret that sentence as a meaningful whole. She is the perfect account [compared to] which her predecessor was not. I don't know enough to support my feeling. On the other hand, I agree the relative pronoun "who" would be wrong although at first glance it looks acceptable. It's a very tricky question, but nonetheless intriguing!
    – Mari-Lou A
    Jul 25, 2022 at 15:53

I’d get a new source.

Although “who” and “whom” are reserved for human beings. your first example is talking about a learned skill rather than the entirety of a human beings. I too would not use “who” in your first example. Moreover, because this is a descriptive rather than a restrictive clause, I agree that “which” is idiomatic rather than “that.”

In your second example, all three options are idiomatic.

There are certain grammatical rules that prohibit “that” initiating a relative clause. For example,

The point on which he and I disagree

is grammatical.

The point on that he and I disagree

is not grammatical.

But, except as objects of prepositions, “that” and “which” are equally grammatical for starting a restrictive relative clause. Moreover, in simple relative clauses, the relative pronoun can be omitted.

Descriptive (non-restrictive) relative clauses, on the other hand, sound unnatural if the relative pronoun is “that.” I am not sure whether using “that” in such cases is an outright grammatical error, but it is not normal usage.

Furthermore, Fowler recommended as a point of style that starting restrictive clauses (when grammatical) with “that” rather than “which” helps your audience distinguish between descriptive and restrictive clauses.

Here are some guidelines.

Use “who” or “whom” when you are talking about persons rather than attributes of persons.

Do not use “that” to introduce a descriptive relative clause.

Do not use the relative pronoun “that” as the object of a preposition.

Except if the object of a preposition, do use “that” rather than “which” to initiate a restrictive relative clause. But remember that this last is a recommendation on style than a rule of grammar.

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