Breakdown of Это рыбак, который сидит на льду.
это
this / it is
на
on, at / by (transport) / to (a place) / to (in answer to)
сидеть
to sit
который
which / who / that (relative pronoun)
Questions & Answers about Это рыбак, который сидит на льду.
Why is the word for ice льду here instead of льде?
The preposition на indicating location usually takes the Prepositional case, which normally ends in -е. However, лёд is one of a special group of short, masculine nouns that take a stressed -у ending in the Prepositional when talking about a physical location (often called the Locative case). Other common examples you have seen include в лесу (in the forest) and на полу (on the floor).
The dictionary form is лёд. Where did the ё go in льду?
The word лёд has what is called a fleeting vowel. When you add a grammatical ending to it, the ё drops out completely. To keep the consonant л soft just like it was in the original word, a soft sign is added, making the base льд-. Once we attach the Locative ending -у, we get льду.
Why is который in the Nominative case here? Doesn't it belong to the second part of the sentence?
Yes, the case of который depends entirely on its grammatical role inside its own clause (the second half of the sentence). Here, it acts as the subject doing the action for the verb сидит (who is sitting), so it must be in the Nominative case. It gets its gender (masculine) and number (singular) from the noun it refers back to, which is рыбак.
The English translation says 'is sitting'. Why is it just and not a continuous form?