thuộc

Etymology 1
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Verb

 * 1)  to belong to, to be subordinate to, or to be under the management of
 * 2)  to be a proper subset of
 * 1)  to be a proper subset of
 * 1)  to be a proper subset of
 * 1)  to be a proper subset of

Etymology 2
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Verb

 * 1) to know (lesson, road, etc.) by heart
 * 2) to tan (leather)