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charge (of something); matter in one's charge; (one's) assignment; (one's) job
彼女の受持ちは三年生のクラスです。
Her assigned class is the third-year students.
この案件は私の受持ちではありません。
This case is not my responsibility.
受持ちの患者さんの様子を見に行った。
I went to check on the patients in my charge.