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to feel down; to feel sad; to be depressed; to be in low spirits
to be in a slump (business, economy, etc.); to be in an unfavourable condition
to fall into (e.g. a hole)
試験に落ちてかなり落ち込んでいます。
I'm feeling down after failing the exam.
今月は売り上げが大きく落ち込んでいました。
Sales was declining.
友人の励ましのおかげで落ち込んだ気持ちが回復した。
Thanks to my friend's encouragement, my depressed feelings recovered.