The Russian T-K Constructions

We've mentioned this problem before but now we will investigate its major implications: case cannot be assigned to clauses but sometimes it needs to be. For example, it is easy to say in English We talked about what you were reading x because what may be in two places at one time: simultaneously serving as the objects of both about and read (invisibly occupying the position 'x'). In Russian, however, the preposition о(б) requires the prepositional case while читать "read" requires its objects in the accusative case.

So what happens when Russians want to say something like "We talked about what you were reading?" First notice that a pronoun like what is required. The problem is that what plays a role in both the main clause and the subordinate one, where different cases are required. Because of the rule above, however, if two cases are required in Russian, two pronouns are required, and that is precisely Russians resolve this problem. The first pronoun is a demonstrative pronoun (usually beginning with 't') and the second is a relative (interrogative) pronoun (usually beginning with 'k' or a related sound), e.g. Мы говорили о том, что вы читали. These constructions are called 'T-K Constructions'. Remember, a comma is required between the two pronouns, as the examples below illustrate.