Biotite is a subordinate constituent of the mafic and ultramafic rocks generally.黑云母一般是镁铁质及超镁铁质岩石中的次要成分.Late Precambrian mafic dyke swarms are extensively developed in the central North China Craton.华北克拉通中部广泛发育晚前寒武纪镁铁质岩墙...
He warned the public to be vigilant and report anything suspicious.他警告公众要提高警惕，遇到任何可疑情况都要报告。A pilot must remain vigilant at all times.飞行员必须随时保持警惕。He has to learn how to remain vigilant through these long nights.他得学会如何在这漫长...