Breakdown of Изобретатель, который сделал этот аппарат, очень умный.
этот
this [f: эта, n: это]
очень
very
сделать
to do (perfective) / to make (perfective)
умный
clever, intelligent
Questions & Answers about Изобретатель, который сделал этот аппарат, очень умный.
Can I use кто instead of который here since it means "who"?
No. While кто means "who" in questions, Russian uses который (which/who) to connect a descriptive clause back to a specific noun (like изобретатель). Кто is generally only used as a connector if there is no specific noun, like in "He who..." (Тот, кто...).
Why is который in the masculine singular Nominative form here?
Который matches the gender and number of the noun it refers to. Since изобретатель (inventor) is masculine and singular, который takes the masculine singular form. It is in the Nominative case because it acts as the subject of the action inside its own clause (it represents the person who did the making).
Is этот аппарат in the Nominative case?
It is actually in the Accusative case because it is the direct object—it is the thing being made by the inventor. However, because аппарат is a masculine inanimate noun (a non-living thing), its Accusative form looks exactly the same as its Nominative form.
Why are there commas around который сделал этот аппарат?
In Russian, relative clauses (parts of a sentence starting with words like который) must always be separated by commas. You need one comma before который to open the clause, and another after аппарат to close it before returning to the main sentence.