dead secret meaning in English

绝对的秘密，绝密

A dead secret
还未泄露的秘密
She leaned back far to look up where the fireworks were and she caught her knee in her hands so as not to fall back looking up and there was no one to see only him and her when she revealed all her graceful beautifully shaped legs like that , supply soft and delicately rounded , and she seemed to hear the panting of his heart , his hoarse breathing , because she knew about the passion of men like that , hot - blooded , because bertha supple told her once in dead secret and made her swear she d never about the gentleman lodger that was staying with them out of the congested districts board that had pictures cut out of papers of those skirtdancers and highkickers and she said he used to do something not very nice that you could imagine sometimes in the bed
除了他和她而外，没有一个人在看着，所以她把她那双俊秀而形态优美娇嫩柔韧而细溜丰腴的小腿整个儿裸露出来。她似乎听到他那颗心的悸跳，粗声粗气的喘息，因为她也晓得像他那样血气方刚的男人，会有着怎样的情欲。还因为一次伯莎萨波尔告诉过她一桩绝对的秘密，并要她发誓永远不说出去。