每日一词【403】undercover：秘密的，暗中进行的

今天我们要学的词是undercover。 Undercover, 是指秘密的，暗中进行的。"An undercover operation," 就是一次秘密行动。最近，美国农业部宣布回收1亿4千3百万磅牛肉。"An undercover video showed that cows too sick to stand were slaughtered for human consumption," 因为一部秘密拍摄的录像显示，加州一家屠宰厂非法宰杀了很多病得站不起来的牛，并将牛肉送入市场。"The undercover investigator refused to disclose his identity for fear of retaliation," 因为担心报复，卧底拍摄录像的调查人员不肯透露自己的身份。好的，今天我们学习的词是undercover...