研磨, 磨碎
reduce (something) to small particles or powder by crushing it
摩擦, 磨擦
rub (something) together or against something else with a harsh, grating sound
苦幹, 刻苦學習
perform a repetitive or tedious task
苦差事, 磨礪
a repetitive or tedious task or period of work
研磨聲, 摩擦聲
the action or sound of grinding