汉语翻译
【医】 半衰期(放射性物质), 半存留期(化学性物质)
英语解释：
名词 half life:
- the time required for something to fall to half its initial value (in particular, the time for half the atoms in a radioactive substance to disintegrate)
同义词：half-life
例句：
- He's been lucky all his life and has never had to find out how the other half lives.
他享了一辈子的福，从来不知道穷人生活的滋味。