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惰性气体元素的原子半径特别大吗？
而在周期表里此行最重的元素，惰性气体氦，用于压力舱那类东西的小裂缝。
The next heaviest element in the periodic table, the inert gas helium, is used for detecting cracks in pressure vessels and the like.
每一周期以惰性气体的主族元素结束。
Each period ends with a member of the family of elements called the noble gases.
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