Das Flugzeug landet am Abend, wenn der Mond schon zu sehen ist.

The airplane lands in the evening when the moon is already visible.

Breakdown of Das Flugzeug landet am Abend, wenn der Mond schon zu sehen ist.

• sein: to be
• dem: the; (masculine or neuter, dative)
• sehen: to see
• der Abend: the evening
• schon: already
• wenn: when
• an: at
• das Flugzeug: the airplane
• der Mond: the moon
• landen: to land

Questions & Answers about Das Flugzeug landet am Abend, wenn der Mond schon zu sehen ist.

Why is am Abend used instead of abends?

am Abend is a prepositional phrase (an an + dem Abend) that points to a specific time (“in the evening” of that day). abends, by contrast, is an adverb meaning “in the evenings” in a habitual or general sense (“every evening”). Since the sentence refers to one particular landing time, you use am Abend rather than the repetitive sense of abends.

Why is wenn used here instead of wann or als?

In German, wenn is the subordinating conjunction for temporal clauses in the present, future or for repeated events (“whenever/when”).

• wann is only used in questions (direct or indirect) meaning “when?”
• als is another temporal conjunction, but it’s reserved for single past events (“when” in the past).
  Because the landing is a future (or general) event, wenn is the correct choice.

Why is there a comma before the wenn‑clause?

German grammar requires a comma to separate a main clause (Hauptsatz) from any dependent clause (Nebensatz). Since wenn der Mond schon zu sehen ist is a Nebensatz introduced by wenn, it must be preceded by a comma.

Why does the sentence use present tense landet if it refers to a future event?

In German, the present tense is often used to talk about future events when a time indication (like am Abend) makes the reference clear. There’s no need for a future construction (wird … landen) if the context already shows it’s in the future.

Why is the verb ist at the end of the wenn‑clause?

In German subordinate clauses (Nebensätze) introduced by conjunctions like wenn, the finite verb is pushed to the very end of the clause. That’s why ist appears last in wenn der Mond schon zu sehen ist.

What does zu sehen ist mean, and why is there a zu?

zu sehen sein is a periphrastic passive‑style construction meaning “to be visible” or “to be able to be seen.” Here zu sehen is an infinitive, and sein carries it. Literally it’s “the moon is to be seen,” which idiomatically means “the moon is already visible.”

Where does the adverb schon go in a German clause, and why is it placed before zu sehen?

German adverbs like schon typically occupy the middle field, after the subject but before the verb cluster. In the wenn‐clause the positions are:

1. wenn (conjunction)
2. der Mond (subject)
3. schon (adverb)
4. zu sehen (infinitive)
5. ist (verb)
   That’s why schon comes directly after der Mond and before the verb group zu sehen ist.