Complex sentences with 'which'
I'm very confused with this kind of sentences. I see them very rarely but it's very natural to speak so in my primary language, so I always try to say it in English.
For example here is a question: "Who is that girl you walked yesterday with?". And now I'm going to answer this question in the same fashion: That girl which I walked with was Masha.
So was it gibberish or correct?
And few more examples:
The country which I'd like to travel to.
The language which I speak.
And can I say it without 'which'? The country I'd like to travel to. The language I speak.
If someone who knows Russian read this, I can ask in simpler way - как перевести предложения, в которых встречаются "в котором", "к которому", "на котором", и т.д.
I hope you got my idea. And thank you in advance.