和英辞書

のだ

phrase

an assertion that emphasizes the cause, reasons, grounds and etc. / determination of the speaker; request to the listener to take a certain action / explain something's look and state exclamatorily

彼が怒っているのは、約束を破ったからなのだ。

The reason he is angry is because you broke the promise.

意味（1）

an assertion that emphasizes the cause, reasons, grounds and etc.

そんなことだからお前(まえ)はいつまで経(た)っても出(しゅっ)世(せ)できないのだ。

Sonna koto da kara omae wa itsu made tatte mo shusse dekinai no da.That's why you never get ahead in your career.

意味（2）

determination of the speaker; request to the listener to take a certain action

一(いっ)刻(こく)も早(はや)く捕(ほ)獲(かく)するのだ。

Ikkoku mo hayaku hokaku suru no da.We must capture it as soon as possible.

意味（3）

explain something's look and state exclamatorily

なんて酷(ひど)いのだ。

Nante hidoi no da.How awful!

意味（4）

an intention to ask for the listener's intention or the facts

一(いっ)体(たい)全(ぜん)体(たい)どう違(ちが)うのだ？

Ittai zentai dō chigau no da?What in the name of God is the difference?