HSK 7-9
宝库
bǎokù名
treasure-house; treasury; treasure-trove (often fig., book of treasured wisdom)
图书馆是知识的宝库。
Tú shū guǎn shì zhī shi de bǎo kù.
A library is a treasure-house of knowledge.
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Appears across levels (7-9) in the HSK 3.0 word list.