Here's a new book. The book is really interesting.
Here's a new book that is really interesting.
Notice how above, in the third sentence, the word that is used as a substitute for the word book? We do this this English to save us from having to repeat the word book twice (like in the first two sentences). Here's a similar example:
Where is the student? The student speaks Russian.
Where is the student who speaks Russian?
Here the word who replaces the word student.
We can do the same thing in Russian using the word который. Let's take another look at two of the sentences from the previous examples example, only this time in Russian:
Вот новая книга, которая очень интересна.
Here's a new book that is really interesting.
Где студент, который говорит по-русски?
Where is the student who speaks Russian?
NOte:
In English we use "that" to refer to things, and "who" to refer to people. In Russian the word который is used to refer to both things and people.
который takes the same endings as adjectives
который changes for gender, case, and number just like Russian adjectives.
Вот новая книга, которая очень интересна.
Notice how "книга" is a feminine noun and so "который" is used with a feminine ending to get: "которая".
Similarly when we're using "который" with the masculine noun "студент", we use it's masculine form:
Где студент, который говорит по-русски?
Here's a couple more examples:
Где дети, которые едут на экскурсию? (Where are the children who are going on the excursion?)
Here "дети" is a plural noun so "который" uses a plural ending.
Вот платье, которое ему так понравилось. (Here's the dress he liked so much.)
Here "платье" is a neuter noun and "который" is used with a neuter ending.
A Closer Look:
Кто vs Который (What's the difference?)
Using который with different cases
So how do we know which case ending to use when we want to build a sentence with который? Let's look at another example:
Где книга, которую вы купили?
Where's the book that you bought?
Here который is used in the accusative form которую, even though in the first part of the sentence книга is in the nominative form. This is because the sentence can be broken into two parts (also called clauses). In the first part we're simply asking "Where is the book?". Thus книга is nominative.
In the second clause "the book" becomes the direct object (remember you are buying the book). Thus которую represents the book that is being bought, and we use the accusative form.
NOte:
The gender and number of который agree with the noun that it refers back to, but the case of the который depends on its function within the second part (clause) of the sentence.
Let's take a look at some more examples where который is used in different case forms:
Они говорили о студенте, которого вчера не было.
They talked about the student who was not there yesterday.
In the second clause we use the genitive form которого to express absence.
Я знаю студента, которому было так скучно.
I know the student who was so bored.
Here the second clause refers to the state of being/feelings of the student so we used the dative которому.
Я думаю о студенте, с которым ты говорил.
I am thinking about the student who you talked with.
In this example we are referring to the student with whom the other person spoke. Thus we use the instrumental form.
NOte:
If you use a preposition with который it must always come before который in the second clause of the sentence.
Я думаю о студенте, с которым ты говорил.
Final thoughts
There are two things I love about который: 1) is pretty easy to understand and use, 2) It allows you to create longer sentences and advance your speaking skills.
If you think of который as an adjective then you shouldn't have too much trouble with this oh so important part of the Russian language. Good luck with your studies and have fun using который!
