たの

did …?

→ いる
phrase Very common #1,244
did …? A casual question pattern: の adds a sense of asking for or confirming an explanation. The form often follows a past-tense verb, including a contraction of ていた to てた.
JA: もう食べたの?
EN: Did you already eat?

トムは遺書を残してたの?

Did Tom leave a will?

トムとメアリーはフランス語で話してたの?

Were Tom and Mary speaking in French?

聞いてたのか?

Were you listening?

— ブレット・トレイン (2022)

隠れてたのね。

So you were hiding.

帰ってたの?

Were you back home?

— 花様年華 (2000)

避妊はちゃんとコンドームつけてたのよね?

You did use a condom properly, right?

私が助けるとか、本気で思ってたの?

Did you really think I’d help you?

私のこと話してたの?

Were you talking about me?

トムって君のこと恐れてたの?

Was Tom afraid of you?

どこ行ってたの?

Where have you been?

— マルホランド・ドライブ (2001)

来てたのか?

Were you here?

— ライフ・イズ・ビューティフル (1997)

最近どこへ行ってたの?

Where have you been lately?

ヒョンソ生きてたのか?

Hyunseo, you're alive?

— グエムル -漢江の怪物- (2006)

トムとメアリーは、英語かフランス語かで話してたの?

Were Tom and Mary speaking in English or French?

楽しく泳いでたのか?

Were you having fun swimming?

— アトランティス 失われた帝国 (2001)

どこに行ってたの?

Where have you been?

— 紅夢 (1991)