arc line的用法和样例：
例句
- Normally, the measured spectral line for the superheated iron atoms would show up as a symmetrical peak.
通常，所测得的超高温铁原子光谱线会显示出一个均匀的尖顶。 - After a little argon was mixed, the breakdown voltage of discharge obviously decreased.The spectral line intensities of nitrogen molecules and nitrogen atoms increased.
在大气中加入少量氩气后，击穿电压明显降低，在相同电压条件下，氮分子光谱线和氮原子光谱线强度都增强。
