然后会出现原子序数，代表了未知元素。

Then, there'd be an atomic number, for which there was no known element.

youdao

清单28展示了一个带有复杂的未知扩展元素的条目示例。

Listing 28 shows an example of an entry with a complex, unknown extension element.

youdao

从那时起，她决心找出这种未知的元素。

From that moment she resolved to trace the unknown element.

youdao

从那日起，她决心找出这种未知的元素。

From that moment she resolved to trace the unknown element.

youdao

从那日起，她决心找出这种未知的元素。

From that moment she resolved to trace the unknown element.

youdao