Metalsmiths knew how to detect forgeries of precious metals by measuring their density, using Archimedes' method of submersion in water to measure volume.

当时的金属匠利用阿基米德把物体浸在水中测量体积的方法，知道如何检测假的贵金属物品。

youdao

Unless rescued by a trained lifeguard, these drowning people can only struggle on the surface of the water from 20 to 60 seconds before submersion occurs.

除非是训练有素的救生员，这些溺水者只能在水面坚持二十到六十秒，之后会沉入水下。

youdao

The floatable bags operate in extreme temperatures of -22F to 140F and protect against water submersion for 30 minutes at a depth of 1 meter, also designed with room to accommodate a few small items such as credit cards, bandages, etc.

ENGADGET: SpareOnePlus adds location tracking, audio alerts, keeps the 15-year life on a single AA battery eyes-on