Breakdown of Lisäksi tarvitsemme lisää aikaa.
aika
time (concept, duration)
lisää
more
tarvita
to need
lisäksi
in addition, furthermore
Questions & Answers about Lisäksi tarvitsemme lisää aikaa.
Both lisäksi and lisää look very similar. What is the exact difference between them here?
Both words are derived from the noun lisä (an addition). Lisäksi is in the translative case (indicated by the -ksi ending) and functions as a linking adverb meaning "in addition" or "furthermore". Lisää is the partitive form of the same word, used here as a quantifier meaning "more".
Why is aikaa in the partitive case?
The partitive form aikaa is required because it directly follows the word lisää. Whenever lisää acts as a quantifier meaning "more", the noun that follows it must be in the partitive case. This is the exact same rule that applies to other quantity words like paljon (a lot) and vähän (a little).
The active verb tarvita often takes an object in the genitive-like accusative case. Why doesn't it here?
You are right that tarvita takes an accusative object when you need a specific, whole item (for example, Tarvitsemme uuden auton). However, that rule doesn't apply here for two reasons: first, "time" is an uncountable, abstract concept; second, the presence of the quantifier lisää forces the object into the partitive case anyway.
How would this sentence change in everyday spoken Finnish?