一瓶子不响，半瓶子晃荡
yī​píng​zi​bù​xiǎng, bàn​píng​zi​huàng​dang

empty vessels

一瓶子不响，半瓶子晃荡 (一瓶子不響，半瓶子晃蕩) yī​píng​zi​bù​xiǎng, bàn​píng​zi​huàng​dang
empty vessels
literally meaning a full bottle is silent while a half-full one sloshes; figuratively, those with limited knowledge boast while the truly learned remain quiet

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