unguarded moment meaning in English

失去警惕的时候

In an unguarded moment he gave away the secret .
他一时没留神泄露了秘密。
No one knew hitler better or saw him more often in his unguarded moments than hess .
没有人比赫斯更了解希特勒，赫斯在希特勒公余之暇见到他的次数也最多。
In an unguarded moment , he give away most important secrets
他一不留神泄露了非常重要的秘密。
He takes as much pains to hide his feelings , as any hypocrite would to conceal his indifference ; but on every unguarded moment the mask drops off , and reveals him to the most superficial observer
伪君子掩饰自己的冷漠无情不遗余力，他却极力掩饰自己的真情实意；不过，不定什么时候他一不小心，假面具掉下来，再粗心大意的人也能看出他的本来面目。
The vicious propensities - the want of principle , which he was careful to guard from the knowledge of his best friend , could not escape the observation of a young man of nearly the same age with himself , and who had opportunities of seeing him in unguarded moments , which mr . darcy could not have
他为人放荡不羁，恶习重重，他虽然十分小心地把这些恶习遮掩起来，不让他最好的朋友觉察，可是究竟逃不过一个和他年相仿佛的青年人的眼睛，他一个不提防就给我瞧见了漏洞，机会多的是当然老达西先生决不会有这种机会。