HSK 7-9
必不可少
bìbùkěshǎoabsolutely necessary; indispensable; essential
耐心是学习中必不可少的品质。
Nài xīn shì xué xí zhōng bì bù kě shǎo de pǐn zhì.
Patience is an indispensable quality in learning.
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Appears across levels (7-9) in the HSK 3.0 word list.