Learn Danish: Efter at have læst bogen forstod jeg mere. - After having read the book, I understood more.

In Danish, when a preposition like efter is followed directly by an action, you must use at plus the infinitive verb. This structure often corresponds to English words ending in -ing, such as saying after having read.

Why is the word order forstod jeg instead of jeg forstod?

This is a classic example of the V2 (verb-second) rule. The entire opening phrase Efter at have læst bogen acts as the first element of the sentence. Because the main verb must come second, the verb forstod swaps places with the subject jeg.

Can I phrase the first part differently, using havde instead of at have?

Yes, you can turn it into a full subordinate clause by adding a subject: Efter at jeg havde læst bogen (After I had read the book). Both versions are natural and commonly used, though the version in this sentence is slightly more concise.

What is the base form of the irregular verb forstod?

The infinitive is at forstå (to understand). Its core forms are forstår in the present tense, forstod in the past tense, and har forstået in the present perfect tense.