書いたの

did … write?

→ 書く
phrase Uncommon #18,899
did … write? The の at the end makes this a casual question, often with a tone of seeking confirmation. The subject or object may be understood from context.
JA: この絵、君が書いたの?
EN: Did you draw this picture?

この本はいつ書いたの?

When did you write this book?

あれって、あなたが書いたの?

Did you write that?

今日の日記は書いたの?

Did you write today’s diary entry?

君が書いたのか?

Did you write it?

— いまを生きる (1989)

その手紙は彼女が書いたのよ。

She wrote that letter.

あなたがそれを書いたの?

Did you write that?

誰がこの手紙書いたの?

Who wrote this letter?

手紙は書いたの?

Did you write the letter?

誰がこれを書いたの?

Who wrote this?

彼女が書いたの?

Did she write it?

この文って、自分で書いたの?

Did you write this sentence yourself?

匿名手紙は彼が書いたのよ

He wrote the anonymous letter.

— 暗殺の森 (1971)