Noun:

1. worthless or dangerous material that should be removed;

   "there were impurities in the water"
   

2. the scum formed by oxidation at the surface of molten metals

rubbishn.垃圾；废物；废话；碎屑v.贬损

trashn.废物；垃圾vt.废弃；捣毁；擦去vi.捣毁

garbagen.垃圾；废物；食物残渣

scumn.槽粕；渣滓；卑贱之人v.形成浮渣；去除浮渣

wasten.废物；浪费；荒地v.浪费；滥用；消耗adj.荒芜的；无用的；浪费的

junkn.垃圾；废旧杂物；中国平底帆船vt.丢弃

impurityn.不纯；杂质

slagn.熔渣；矿渣；<英俚> 荡妇v.(英）严厉批评

scorian.熔渣；金属渣；火山渣

1. They tried to purge metal of dross.
   他们试图清除金属熔化时浮升表面的渣滓。
2. For foreign cultures, we should discard their dross and select their essence.
   对于外来文化，我们要取其精华，去其糟粕。
3. The best players have gone off to the big clubs, leaving them the dross.
   最好的队员都投奔大俱乐部去了，留给他们这些不怎么样的球员。
4. What's gold and silver? Mere dross.
   金银财宝，身外之物。