Der Nachbar ließ die Tür absichtlich offen.

the door

Breakdown of Der Nachbar ließ die Tür absichtlich offen.

• der Nachbar: the neighbor
• offen: open
• absichtlich: deliberately

Questions & Answers about Der Nachbar ließ die Tür absichtlich offen.

What does ließ mean here—is it “let” or “left”?

Here ließ is the simple past of lassen meaning “to leave (something in a certain state)”, not “to allow/let.” So the sentence means “The neighbor deliberately left the door open.”
Example: Er ließ das Licht an. = “He left the light on.”

Why is it ließ (simple past) instead of the present perfect?

Written German often prefers the simple past (Präteritum). In everyday speech, the present perfect (Perfekt) is more common:

• Der Nachbar hat die Tür absichtlich offen gelassen.

Note the placement: the participle is gelassen, and the state word stays with it: offen gelassen.

How does the structure die Tür … offen work?

It’s “object + predicative adjective.”

• die Tür is the direct object.
• offen describes the resulting state of that object.
  Predicative adjectives in German are not declined:
• Er ließ die Tür offen. (predicative, uninflected)
• Compare: die offene Tür (attributive, inflected).

Why is it die Tür (accusative) and not something else?