生锈

to rust / to grow rusty / to corrode / oxidization

to be born / to give birth / life / to grow / raw / uncooked / student

to corrode / to rust

a "screw that never rusts" — sb who selflessly and wholeheartedly serves the Communist Party, like Lei Feng 雷鋒|雷锋[Lei2 Feng1], to whom the metaphor is attributed

a blade will get rusty if it is not sharpened; a man will fall behind if he doesn't study (idiom)

lit. brains rusty / ossified thinking