Learn Hardcore Finnish: Kengät kastuvat nopeasti.

It’s the nominative plural of kenkä (shoe). Subjects in basic statements are in the nominative, and the plural nominative adds -t to the stem: kengät = “shoes.”

Why is it kengät and not “kenkät”?

Consonant gradation. The word kenkä has the strong grade nk in the nominative singular. In many inflected forms (including the nominative plural), nk weakens to ng. Hence: kenkä (sg) → kengät (pl).

How do you pronounce the ng in kengät?

As a long “ng” sound (a long velar nasal), like the “ng” in “singer,” but lengthened. There is no separate “g” sound. Roughly: “ken-ngät.”

Why is the verb kastuvat plural, and what is its person/tense?

Because the subject (kengät) is plural. Kastuvat is 3rd person plural, present tense: “(they) get wet.”

Why does the ending here look like -vat instead of -vät?

Vowel harmony. The verb stem kastu- contains back vowels (a, u), so the 3rd person plural ending uses the back-vowel form -vat. With a front-vowel stem, you’d get -vät.

Is kastua transitive or intransitive? Are there related verbs?

Kastua is intransitive: “to get/become wet.” Related:

kastaa: transitive, “to dip/baptize/wet (something).”
kastella: transitive, “to sprinkle/water/wet repeatedly or lightly.”

How does kastua conjugate in the present indicative?

minä kastun
sinä kastut
hän kastuu
me kastumme
te kastutte
he kastuvat

How would I say this in the past or in the perfect?

Past (preterite): Kengät kastuivat nopeasti. (“The shoes got wet quickly.”)
Perfect (have gotten): Kengät ovat kastuneet nopeasti. Here kastunut/kastuneet is the past participle.

Can I say “Kengät ovat kastuvat”?

No. Finnish doesn’t stack “be” with a finite main verb. Use either the finite main verb (kastuvat) or a periphrastic tense with olla plus the participle (ovat kastuneet).

Why is it nopeasti and not nopea?

Adverbs of manner are formed with -sti from adjectives: nopea (fast) → nopeasti (quickly). You use the adverb to modify the verb.

What are the comparative and superlative adverbs of nopeasti?

Comparative: nopeammin (more quickly)
Superlative: nopeimmin (most quickly)

Can I change the word order? What changes in meaning?

Yes, for emphasis/focus.

Neutral: Kengät kastuvat nopeasti.
Emphasizing how fast: Nopeasti kengät kastuvat. (Focuses on “quickly.”) Word order in Finnish often signals what’s being highlighted.

How do I ask a yes–no question with this sentence?

Attach the clitic -ko/-kö to the verb and keep normal order:

Kastuvatko kengät nopeasti? (“Do the shoes get wet quickly?”)

How do I negate it?

Use the negative verb ei + the main verb in its connegative form:

Kengät eivät kastu nopeasti. (“The shoes don’t get wet quickly.”)

How do I refer back to kengät with a pronoun?

Use the 3rd person plural pronoun ne:

Ne kastuvat nopeasti. (“They get wet quickly.”) This is common after kengät has been mentioned.

Is kengät definite (“the shoes”) or indefinite (“shoes”)?

Finnish has no articles. Kengät can mean “the shoes” or “shoes” depending on context. You can add determiners if needed: nämä kengät (these shoes), ne kengät (those/the shoes just mentioned).

How would I say “My shoes get wet quickly”?

Kenkäni kastuvat nopeasti. You can add the pronoun for clarity or emphasis: Minun kenkäni kastuvat nopeasti. (The possessive suffix -ni marks “my.”)

Is “Kengät kastuu nopeasti” acceptable?

That’s common colloquial (spoken) Finnish, where the 3rd person singular form is used with plural subjects. In standard written Finnish, use kastuvat: Kengät kastuvat nopeasti.