Questions & Answers about Der alte Baum ist endlich in den Fluss gefallen.
This sentence uses ist gefallen (fell). What is the transitive equivalent of this verb, and how would it change the sentence?
The transitive counterpart (meaning "to fell" or "cut down") is fällen, which is a weak verb. If someone cut the tree down, you would use fällen with the auxiliary haben and a direct object: Der Mann hat den Baum gefällt (The man cut down the tree). Since the tree falls on its own here, we use the strong, intransitive verb fallen.
Why does this sentence use ist instead of hat as the helping verb for gefallen?
Because fallen (to fall) expresses a change of location, it requires sein (ist) in the perfect tense. If you used haben (hat gefallen), it would change the meaning entirely! Gefallen is also the past participle of gefallen (to please/like). For example, Der Baum hat mir gefallen means "I liked the tree," not that it fell.
Why is it in den Fluss (accusative) instead of in dem Fluss (dative)?
in is a two-way preposition. Because the tree is moving into the river (showing a destination), we use the accusative case (den Fluss). If the tree were already lying in the river (fixed location), you would use the dative: Der Baum liegt in dem Fluss.
Why is the adjective ending and not since is a masculine noun?