秘密地，暗中
1. 信任：in conclusion最后,总之 | in confidence信任 | in consequence因此,结果
2. 悄悄的,秘密的：gain confidence 获得信心 | in confidence 悄悄的,秘密的 = secretly | take sb. into one's confidence 以某人为心腹
3. 秘密地：in conclusion最后,总之 | in confidence秘密地 | in consequence因此,结果
4. 当作秘密：you should have more confidence in yourself 你应该增强自信心. | in confidence 当作秘密 | I am telling you this in confidence 我现在告诉你的这件事情是个秘密 (strict confidence 绝密)