Relative pronouns: which vs. that

[masajac]

Test No. errors/elem-5 "Relative Pronouns", question 2

I don't understand a word what you are talking about.

(a) a
(b) what
(c) are

Test No. errors/elem-5 "Relative Pronouns", answer 2

I don't understand a word that you are talking about.

Correct entry: that
The error was: (b) what
_________________________

I don't understand why we can't use 'which' instead of 'that'. Please tell me the reason.

[Mister Micawber]

.
Which is normally reserved for non-restrictive (non-defining) clauses.

My red sneakers, which I am not wearing at the moment, are out of fashion.
.
_________________
Native English teacher at Mister Micawber's

[Mkostya]

I am sorry, but I am strongly disagree with the correct answer.

My answer was: "the", i.e. the sentence is I don't understand the word what you are talking about
Explanation: You are explaining me meaning of some word, but I don't understand it. "The" is used since the word is specified by the clause "what you are talking about".

If we use "that", then the meaning changes:

I don't understand a word that you are talking about - You are talking about some topic and I don't understand any word of it. In my opinion it should have been

I don't understand a word from that you are talking about - therefore I didn't choose this answer.

[Mister Micawber]

I'm sorry, Mkostya, but all of your sentences are of strange composition.

'A word' here is idiomatic. It means 'anything, any part of': I don't understand any part of what you are talking about.
_________________
Native English teacher at Mister Micawber's

[Bhikkhu1991a]

Hello,

Could you please double-check why “which” is marked incorrect in this test sentence of Question 2?

According to online dictionaries such as (http://www.macmillandictionary.com/dictionary/british/which) and (http://education.yahoo.com/reference/dictionary/entry/which), “which” is also used in Restrictive (Defining) relative clauses. Please take a look at the entries of the two dictionaries for the word “which” (Pronoun) under Definition 2 and Definition 2 (c) respectively.

Thank you.

Best wishes,
Bhikkhu1991a.

[Mister Micawber]

Here it sounds extremely awkward, Bhikkhu. In any case, the software only accepts the best answer, not all possible answers.
_________________
Native English teacher at Mister Micawber's