当某一层排满电子时，周期表中的下一元素就启用新的一层，此即标志着周期表新的一行元素的开始。
When a shell is full, the next element in the series starts a new shell, and that marks the beginning of a new row of the table.
字转行：各种文字处理或内文处理系统所具备的功能。当察觉排满一行字时，自动把跟着的文字回转下一行。
Word wrap: a feature of all word processing and other text handling systems that wraps text automatically to the next line when a line end is encountered.
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