Breakdown of Они впадают в глубокий сон, ожидая весну.
они
they
в
in / to (direction)
весна
spring
глубокий
deep
Questions & Answers about Они впадают в глубокий сон, ожидая весну.
Since this lesson is about words like вёснами (in the springs / every spring), why is весну used here instead?
In this sentence, spring isn't the time when the action happens, but rather the thing being waited for. Весну is the direct object (Accusative) of the verb ожидать (to wait for). If you wanted to say they sleep during the springs, you would use the Instrumental вёснами, but here they are waiting for the next spring to arrive.
What form is the word ожидая?
It is a present verbal adverb (sometimes called a gerund), meaning "while waiting." It is formed from the imperfective verb ожидать and is used to show a background action that happens at the same time as the main verb (впадают). It must always share the same subject (они) as the main verb.
I remember that verbs meaning "to wait" often take the Genitive case. Why is весну in the Accusative case?
Verbs like ожидать and ждать take the Genitive for abstract concepts or things whose arrival is uncertain. They take the Accusative for specific, concrete things or people. Because spring is a definite, guaranteed event, using the Accusative (весну) is very natural here, though the Genitive (весны) would also be grammatically acceptable.
Why does впадают в глубокий сон use the Accusative case instead of the Prepositional?