HSK 7-9
功底
gōngdǐ名
training in the basic skills; knowledge of the fundamentals
她的书法功底十分扎实。
Tā de shū fǎ gōng dǐ shí fēn zhā shi.
She has a solid foundation in calligraphy.
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Appears across levels (7-9) in the HSK 3.0 word list.