half life
half life 英 [hɑ:f laif] 美 [hæf laɪf]
n. 半衰期；半存留期；半排出期
名词复数:half lives
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- n. 半衰期；半存留期；半排出期
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1. Iodine-131 has a relatively short half life─its radioactivity drops by half in eight days─meaning it naturally becomes safer somewhat quickly.
碘- 131的半衰期相对较短，八天内其放射性水平会下降一半，这意味着其很快就会变得较为安全。
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2. Cesium-137 has a half life of 30 years, meaning that its radioactive emissions will decline only by half after 30 years and affect the environment over several generations.
铯137半衰期为30年，也就是说，其放射性要到30年过后才会减弱一半，将会对环境造成为时几代人的影响。
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3. Most people are not aware that caffeine has a half life of up to eight hours and can affect not only your ability to fall asleep, but also the quality of sleep you are getting.
大多数人都不知道，咖啡因有一个长达八小时的半衰期，不仅会影响你的入睡能力，而且还会影响你的睡眠质量。
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