So we want to look at any element that has a 3 p orbital filled, but that does not then go on and have a 4 s, because if it had the 4 s filled then we would actually see six lines in the spectrum.

所以，我们要找一找有哪些元素的,3，p，轨道被占据，但没有，4，s，轨道被占据,因为如果，4，s，轨道也被占据了,那我们会在光谱中看到第六条谱线。

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