Questions & Answers about Wer hat diesen großen Baum gefällt?
Why is the participle gefällt used here instead of gefallen?
This highlights the difference between this specific transitive and intransitive verb pair. The verb fällen means to cut down or to fell. It requires a direct object (the tree) and is a weak verb, so its past participle is gefällt. The verb fallen means to fall. It has no direct object and is a strong verb, so its past participle is gefallen.
If the verb were fallen (to fall) instead of fällen (to fell), would the helping verb change?
Yes! Because fallen is an intransitive verb representing a change of state or motion, it uses sein as its helping verb in the perfect tense (for example, Der Baum ist gefallen). However, fällen is a transitive verb that takes a direct object, so it always uses haben as its helping verb, as seen here with Wer hat ... gefällt?
Does the umlaut in fällen tell us anything about its relationship to fallen?
Yes, this is a classic morphological shift in German. Historically, a sound change mutated the root vowel a in fallen into an ä, creating the new verb fällen. This shift was commonly used to create weak transitive verbs (meaning you cause an action to happen) out of strong intransitive ones (where a subject simply experiences the action).
Why do both diesen and großen end in -en?