Learn Finnish: Hän luki, kunnes ilta tuli. - He read until evening came.

luki is the past tense of lukea (to read). For the hän (he/she) form, you drop the ending -ea and add the past tense marker -i. Notice that it keeps the strong k just like the present tense hän lukee.

What is the difference between kun and kunnes?

They look very similar, but kun means 'when' while kunnes means 'until'. You use kunnes to show that an ongoing action continued right up to a specific event.

Why is there a comma before kunnes?

In Finnish, you almost always put a comma between two clauses (parts of a sentence that each have their own subject and verb). Since hän luki (he read) and ilta tuli (evening came) are both complete actions, the comma is grammatically required to separate them.

Is it natural to say a time of day 'comes' in Finnish?

Yes! Just like in English, Finnish uses the verb tulla (to come) to describe a time of day arriving. Ilta tuli is the standard and natural way to express that 'evening came' or 'it became evening'.