Questions & Answers about Laukku on täynnä kirjoja.
Why do we use täynnä instead of the basic adjective täysi?
When expressing that something is 'full of' something else, Finnish uses the essive case form täynnä as an invariable state adverb. You would use täysi when it acts as a normal adjective modifying a noun directly, like in täysi laukku (a full bag).
Why is kirjoja in the partitive case rather than the elative case, since the English translation is 'full of books'?
It is a common trap for English speakers to try and translate 'of' using the elative case (-sta/-stä). However, the state adverb täynnä directly requires the word following it to be in the partitive case. Therefore, 'books' must be in the partitive plural: kirjoja.
How does täynnä fit into this lesson's topic of state expressions?
While not a two-word absolute phrase like kädet taskussa (hands in pocket), täynnä operates on the exact same logic. It is a frozen form (the essive case of täysi) functioning as an independent adverb of state. It describes the condition the bag is in, rather than acting as an adjective that agrees with the noun.