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being familiar with; having a thorough knowledge of; being well-informed about
彼は地元の地理を熟知している。
He has thorough knowledge of the local geography.
この分野を熟知した専門家が必要だ。
We need an expert well-versed in this field.
規則を熟知した上で判断すべきだ。
One should judge after fully understanding the rules.