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to know; to understand; to be aware of; to regard as; to take for
to (understand and) accept (a responsibility)
to have a knowledge of (a skill, art, etc.); to have a command of; to know (how to do)
彼は礼儀作法をよく心得ている人だね。
He understands etiquette well.
彼女は接客の仕方をしっかり心得ている。
She knows how to serve customers.
基本的なマナーは心得ておくべきだ。
You should know basic manners.