ではないか
(De ha nai ka)
Used to express surprise, discovery, or to strongly assert an opinion.
Connection rules
- +Noun + ではないか
- +Verb (Dictionary form) + ではないか
Examples
1.
素晴らしいアイデアではないか。

Subarashii aidea de ha nai ka.
Isn't that a wonderful idea?
「Manager praising a plan」
2.
君も一緒に行くと言ったではないか。

Kimi mo issho ni iku to i ta de ha nai ka.
You did say you were going together, didn't you?
「Reminding a friend」
Practice
Wait, didn't you pass the exam?! (Surprised discovery)
えっ、君、___。おめでとう!
Romaji also accepted