HSK 4
究竟
jiūjìng副（名）
to go to the bottom of a matter; after all; when all is said and done; (in an interrogative sentence) finally
你究竟为什么不同意。
Nǐ jiū jìng wèi shén me bù tóng yì.
Why exactly do you disagree?
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Other HSK words sharing a character
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Appears across levels (4（5）) in the HSK 3.0 word list.