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deeply; keenly; severely; completely; utterly
intently; carefully; closely; attentively
彼の話を聞いて熟反省させられましたよ。
I keenly felt my own immaturity.
熟自分の未熟さを痛感する出来事でした。
Thinking deeply about it makes me sad.
熟考えてみると彼の言う通りだと思いました。
When I really thought about it, I agreed with him.