State Department Spokesman Ian Kelly said Mitchell,on his fourth trip to the region since assuming the envoy post in January, will stop in Beirut Thursday and Damascus Friday and Saturday after Jerusalem-based meetings with Israeli and Palestinian officials.

VOA: standard.2009.06.09

So if we're talking about the fourth excited state, and we talk instead about principle quantum numbers, what principle quantum number corresponds to the fourth excited state of a hydrogen atom.

如果我们说的是,第四激发态，我们用,主量子数来描述，哪个主量子数对应了,氢原子的第四激发态？

麻省理工公开课 - 化学原理课程节选