Below is a text with blanks. Click on each blank, a list of choices will appear. Select the appropriate answer choice for each blank.
下面的文本有一些空格。点击每个空格会出现一组选项，请为每个空格选出最合适的答案。
Uniquely stable, they to participate in no chemical reactions. But by understanding the stability of the noble gases, physicists discovered the key to chemical bonding . Dmitri Mendeleev added the noble gases to his periodic table in 1902, where he arranged the elements in rows and columns to their atomic weight. Mendeleev was able to see repeating (or periodic) patterns in their properties. The noble gases appeared in the periodic table, occurring in every eighth position, at least amongst the lighter elements.
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