Questions & Answers about Внутри заповедника мы нашли озеро.
Why is заповедника in the genitive case here?
The preposition внутри (inside) always requires the genitive case. Since заповедник is a masculine noun ending in a consonant, it adds -а to form the genitive.
What is the origin of the word заповедник?
It comes from an old root meaning to command or forbid, seen in words like заповедь (commandment). A заповедник is a strict nature reserve where human activity and hunting are forbidden by law to protect the environment.
Why use the perfective verb нашли instead of the imperfective находили?
You use the perfective нашли because finding the lake was a single, completed event with a clear result. The imperfective находили would imply you repeatedly found lakes over time.
Why does the direct object озеро look like it is in the nominative case?
It is actually in the accusative case because it is the direct object of the verb. However, for inanimate neuter nouns like озеро, the accusative form is completely identical to the nominative form.