throw-away bit一次: once磨损: wear and tear; abrasive wear ...报废: announce invalidated check i ...的: 4次方是 The fourth power of 2 i ...钻头: boring crown; bore bit; dril ...下载手机词典可随时随地查词查翻译关注微信公众号：chachacidian，回复:一次磨损报废的钻头，即可在微信中查询翻译
