碳有两个非放射性的同位素，在太阳系的物质中，包括在大多数的陨石矿石中，它们的混合比例是众所周知的。
Carbon has two non-radioactive isotopes, and in material from the solar system, including most meteoritic minerals, these are mixed in a well-known ratio.
遗憾的是，这种离子交换技术所捕获的非放射性铁离子比放射性钴离子还多得多。
Unfortunately, the ion-exchange technique traps many more non-radioactive iron ions than radioactive cobalt ones.
但是如果处于危险环境的人们预先摄入含有非放射性碘的药物，这些碘就会先到达甲状腺并且有效地防止对放射性的碘的吸收。
But if people at risk receive tablets containing non-radioactive iodine, this reaches the thyroid first and effectively prevents the radioactive isotopes being absorbed.
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