inu ha kaidan wo agareru.

– は is the topic marker. It tells us “as for the dog…,” setting 犬 as the topic of the sentence.
– が marks the grammatical subject, often introducing new information (“a dog can climb”). Here the speaker assumes you know they’re talking about the dog, so は is more natural.

– を marks 階段 as the direct object or “path” of motion. In motion verbs like 上がる (“to go up”), を indicates what you’re going up.
– So 階段を上がれる literally means “(one) can go up the stairs.”

– 上がる is the plain “to go up.”
– 上がれる is its potential form, meaning “can go up” or “is able to go up.” We use it when expressing ability.

1. 上がる is a Godan (u-verb).
2. Drop the final -る and change the -u vowel sound to -e, then add -る.
   – 上がる → 上が＋る → 上がれ＋る = 上がれる.

– 上がる is an intransitive Godan verb (you don’t “raise” something; you yourself “go up”).
– All Godan verbs form potential by changing the -u to -e + -る, unlike Ichidan verbs (which just replace -る with -られる).

– Yes: 犬は階段を登れる。
– 登る (のぼる) often implies climbing a steeper or more challenging ascent (a mountain, ladder), while 上がる is more general “going up” (stairs, steps, stage).
– In everyday speech, both are fine for stairs; nuance is slight.

– Yes, it’s grammatical: 犬は階段を上がることができる。
– This uses the nominalizer こと + できる (“to be able to”).
– It’s a bit more formal/wordy than the concise potential form 上がれる.

In Hepburn romanization:
Inu wa kaidan o agareru.
(Note: the particle を is pronounced “o,” not “wo.”)