in black and white
in writing or in print (regarded as more reliable, credible, or formal than speech)
白纸黑字的,书面的,非口头的
she had abandoned all hope of getting her contract down in black and white.
她对以书面形式把合同肯定下来已不抱任何希望了。
in terms of clearly defined opposing principles or issues
非对即错,非好即坏
children think in black and white, good and bad.
孩子们认为一切不是黑就是白,不是好就是坏。