融合重氢同位素需要大量能量，部分原因是因为原子核带正电并相互排斥。
Fusing heavy hydrogen isotopes requires lots of energy, partly because the nuclei are positively charged and repel each other.
重水因含重氢而得名。重氢是氢原子的一种，其原子核中含有一枚中子，加之正常氢元素中的质子，重量为一般氢原子的两倍。
Heavy water gets its name because it contains deuterium, a form of hydrogen that has a neutron in its nucleus as well as the usual proton and thus weighs twice as much as the ordinary sort.
重氢是原子核中多一个中子的氢。
A deuterium atom is a hydrogen with an extra neutron in its nucleus.
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