Not see the light of day 不对公众公开 make available to the public，保持机密，不发表，隐藏
例句：
Trust me, your manuscript won’t see the light of day if you don’t have a good literary agent.
That document contains far too (太; 极其) much sensitive information. Make sure it never sees the light of day.
Measure 量度为……
It measures 170 meters in length.