意思是或”“Inadvertently give away one's secret identity 非故意地泄漏秘密" （此处cover以为隐藏,名词.hiding sth,）eg：Mary came to the annual meeting pretending to be a shareholder and hoped no one would blow her cover.玛丽假装自己是股东去参加年会,她希望不会有人发现. It would only take one phone call to blow their cover.只要拨打一个电话就可揭穿他们的伪装.（此句摘自牛津高阶.）
