Learn Hardcore Esperanto: Kiam mi legas libron, mi sentas ĝojon.

Kiam is a subordinating conjunction meaning when. It introduces the temporal clause and tells us under what circumstance the main action occurs.

Why do the verbs legas and sentas end with -as, and what does that signify?

In Esperanto, the ending -as marks the present tense. This means that legas translates as “read” or “am reading” and sentas as “feel” or “am feeling” in the present, reflecting ongoing actions.

Why is libro changed to libron in this sentence?

When a noun functions as the direct object in Esperanto, it takes on the accusative ending -n. Here, libro becomes libron because it is the object of the verb legas (to read).

Is the comma after libron necessary, and how does punctuation in Esperanto compare to English in this instance?

Yes, the comma is used to separate the subordinate clause (Kiam mi legas libron) from the main clause (mi sentas ĝojon). This usage is similar to English, where punctuation helps clarify the sentence structure and emphasizes the relationship between the clauses.

Do we need to repeat the subject mi in both clauses, or can it be omitted in the second clause?

While Esperanto’s free word order allows for some flexibility, each independent clause typically includes its own subject for clarity. Even though both clauses refer to the same subject, repeating mi is common—especially for learners—to clearly signal who is performing the actions in each clause.