铁点污染；
"the plane was just a speck in the sky"
同义词：pinpoint
(nontechnical usage) a tiny piece of anything同义词：atommoleculeparticlecorpusclemote
a slight but appreciable addition同义词：touchhinttingemitepinchjotsoupcon
v.produce specks in or on"speck the cloth"
a speck of一点点