关于under第六辑：1. under cover 秘密地，The police officer went under cover to look for the drug dealers.这个警官秘密调查贩毒分子。2.under one's nose在某人眼皮底下，公然地，He flirted with a girl under his wife's nose. 他在他老婆的眼皮子底下跟一个女孩眉来眼去的